[APP] App Finder: The most advanced search engine for Android apps

Skyica

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App Finder
Innovative advanced search engine for Android apps and games

2,300,000+ apps from Google Play are indexed, with data for all 200+ countries/regions.

Available as an app, a web interface is coming soon.


Feature Overview

The features in italics require a Plus license for a small fee
The other features are always free, without ads


  • Powerful search language
    • Usual search operators like quotes, OR, and minus
    • Special operators, e.g. + to require words to occur in title or summary
    • The search terms are highlighted in the results (the app descriptions)
      .
  • 10+ filters and 6 sort options
    • Filter for apps without ads, for free / paid apps, for apps with / without in-app purchases
    • Category filter with multi-select
    • User rating filter (0.1 star steps) for country-specific or world-average rating
    • Filters for number of ratings and downloads
    • Filters for update date and release date
    • Filters for price range and in-app price range for local prices
    • Filter for the minimally required Android version
    • Age rating filter for local ratings
    • Sort by relevance, user rating, number of ratings up / down, and release date up / down
      .
  • 10+ essential data about every app directly in the result list
    • Average user rating with two decimals, country-specific or world-average or both
    • Number of ratings and downloads with two significant digits
    • Unique visual representation of the rating distribution
    • Update date and release date
    • With or without ads
    • Local price and price range of in-app purchases
    • Category
    • Age rating from the local rating authority
    • Required Android version
    • Short description
    • Result list can be customized
      .
  • Details view and links to Play Store and Google Play website
    • In the details view, all information is shown also without Plus license
    • It can be swiped sideways for the next / previous app
    • The apps can be opened in the Play Store app, directly from the result list
    • There are also links to the Google Play website so that language or country can be changed to see more reviews
      .
  • Scalable screenshots in the result list
    • The feature graphics are displayed along with the screenshots
      .
  • Flexible user interface
    • The UI scale can be adjusted independent from the system settings
    • The interface adapts to screen-size and -orientation, and selected UI size
    • Many options, 1-, 2-, or 3-pane layout
    • Optimized for tablets also
      .
  • Easy to use, with integrated documentation
    • Also available here

Major upcoming features
  • A web interface
  • Indexing of other app stores, later also iOS apps
  • Support for other languages
  • Recommendations of apps based on apps the user has installed
  • Possibility to add apps to custom lists from the search results
  • Search history
  • Search language improvements, e.g.
    • search for exact words
    • automatic inclusion of synonyms
    • later semantic (AI) search as alternative
  • Display of world-average rating for apps without local rating, and as alternative to local rating
  • Display of two decimals for high ratings (consider two apps rated 4.86 and 4.94 stars respectively, which are both rounded to 4.8 stars by Google Play)
  • Display of ratings calculated from top-liked reviews (the average rating of the first reviews sorted by relevance by Google Play. This often differs significantly from the rating calculated by Google Play, and is in my experience mostly a much better indicator for the quality of the app, especially for apps with many fake reviews)
  • Display of permissions, possibly filters for important permission groups
  • A dark theme
  • Comprehensive documentation
  • Interactive tutorials

Get it on Google Play


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User Guide

If anything is unintelligible, or if you think that more or less explanation is needed, please let me know!

To search,

please do the following:
  • Enter a query consisting of keywords and possibly search operators,
  • Optionally, activate filters like app category and minimum user rating,
  • Optionally, change the sort order.
You may also just select a category without entering a query.

Keywords and Search Operators

When you type a query into the search box, App Finder matches it against the descriptions of the apps in a clear and easily comprehensible way, described below.

Please note: Unlike Google, App Finder does not use semantic search. That is, it does not try to understand your query as natural language.
While semantic search may be easier to use, App Finder gives you more control and certainty about how the search is executed.

In the simplest case, if you just enter keywords separated by spaces, it returns exactly those apps where all the words (or forms of them, like the plural) appear in the description (or title or developer name).

To refine the search, you may use various search operators, completely described in Search Syntax below.
  • Common operators include quotes to search for phrases, minus to exclude words, and OR for alternatives.
    .
  • An operator specific to App Finder is +, which can be very useful to narrow down your search.

    + in front of a word requires it to occur in title or summary, not just anywhere in the description (the summary is the short description that appears in the result list).
    .
  • Further, there is the special OR operator /. Unlike the usual OR, it is evaluated before all other operators. Also, it can be used inside quotes.

    For example, to search for file managers (that are sometimes called file explorer), you may type

    “file manager/explorer”,

    which is equivalent to

    “file manager“ OR “file explorer”.

    Adding the + operator gives a search for file managers that is quite comprehensive and specific:

    +”file manager/explorer”.
    .
Please note that App Finder currently does not consider synonyms automatically, so / should always be used to list synonyms if needed.

Relevance Sort

While the other sort options are quite clear, some explanation is needed for the default relevance sort.

Here the results are ranked by a combination of a query match score and a user rating and popularity score.

The query match score increases with your keywords occurring in the app title, the summary, or occurring early or frequently in the description.

The rating and popularity score increases with the average user rating, the number of ratings, and the number of downloads.

While a high rating and popularity score is an indication that an app is much liked by many people, it is of course no guarantee for the quality of the app (especially since fake reviews are a big problem on Google Play).

We do not recommend the apps at the beginning of the list over the other apps in any way.

Country-Specific Data


App Finder has local data (app availability, prices, age-ratings, and average star-ratings) for all countries supported by Google Play. The country can be changed from the Settings menu.

Please note that App Finder currently searches and displays the app descriptions in English only, irrespective of the selected country.

Reading the Result List

  • The number left of the stars is the average user rating calculated by Google Play.
    .
  • The stars represent the rating distribution:

    The size (that is, area) of the stars is proportional to the number of 5-, 4-, 3-, 2-, and 1-star ratings (from green to red).

    Between different apps, the star-size is correlated with the total number of ratings at a logarithmic scale.
    .
  • Paid apps without an indication do not contain ads.

    For apps with in-app purchases, the price range is shown bottom right.
    .
  • A + after the result count indicates that only the app summaries have been searched, not the full descriptions. This is to show you the most relevant apps in the case of searches with very many results.

    You can double-tap the result count above the result list to repeat the search without the limitation.
    .
Using the Result List
  • Tap the icon of an app to view it on Google Play, tap somewhere else to see the details in App Finder.

    You can swipe the details-view left / right to view the next / previous app.
    .
  • To change the size of the screenshots, use two fingers anywhere on the result list as if you would zoom a photo (requires a Plus license).

    To hide or show the screenshots, tap the picture icon top right.
    .
  • For more or less data, or to change the text size, tap the cog icon.
    .
Adjusting the User Interface

To change the size of text and other elements, select Screen Zoom from the Settings  menu.

The screen orientation is locked to portrait on phones and to landscape on tablets by default. However, it can be unlocked in the Display Options from the Settings  menu.

Depending on the screen-size, -orientation, and -zoom, a 1-, 2-, or 3-pane layout is used.


Search Syntax

App Finder's search is based on PostgreSQL's powerful text search. To make the use as easy as possible, App Finder understands queries in the following succinct language, which are then translated to PostgreSQL's syntax.

  • If the query consists only of words separated by spaces, exactly those apps are returned where all the words (or forms of them, see below) appear in the description or title or developer name.

  • Different forms of a word are equated, but synonyms are not considered currently. Examples for forms of words that are equated are
    .
    • file = files = file’s
      .
    • quick = quickly, but quick quicker, and quick quickest
      .
    • edit = edits = edited = editing, but edit editor
      .
  • Capitalization does not matter.
    .
  • Words separated by / are alternatives, that is, only one of them is required to appear.
    .
    • No spaces are required around /.
      .
    • Unlike the usual OR-operator, / is evaluated first, which makes it often possible to avoid parenthesis and repetitions.
      .
    • For example, file manager/explorer means that in addition to file, either manager  or explorer  must appear.
      .
  • The usual OR is also supported.
    .
  • Words inside quotes are required to appear in sequence.
    .
    • Note that different word forms are still allowed.
      .
    • / is also allowed inside quotes.

      For example, "file manager/explorer" is equivalent to "file manager” / “file explorer”.
      .
  • - in front of a word requires it (and its forms) to not occur.
    .
  • + in front of a word requires it to occur in title or summary.
    .
  • The order of operations is /, +, -, the spaces denoting AND, OR.
    .
    Parentheses can be used to change the order.
 
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I have just added a search syntax reference to the user guide.

I think that all information needed to use App Finder optimally is now included.

As listed in the upcoming features, the possibility to search for exact words and to include synonyms automatically will be added soon. Further, semantic (AI) search is planned as an alternative for later.
 

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App Finder 1.0.9 released with important new features

With this update, the world average user rating is now shown for apps without country specific rating.

Also, the world average can be shown instead of or in addition to country specific rating. World average rating can also be used for filter and sort.

Why this is important

As you are probably aware, Google Play shows country specific ratings since some time.

While these have obvious advantages, they also have the disadvantage of being based on the opinion of fewer people, or not being available at all for apps with too few ratings in the respective country.

In the following, I will explain this more exactly.

First you should know that Google Play shows localized ratings only for some countries, for the others the world average is shown.

Here is the complete list of countries with localized ratings, with the percentage of apps for which ratings are shown on Google Play (with regard to all apps available in the respective country).

It is based on data we have scraped a few days ago from the Google Play website for nearly 2.4 million apps, for 181 countries each.

Rich (BB code):
United States       20%
India               19%
Brazil              13%
Indonesia           12%
Russia              11%
Germany             10%
United Kingdom      10%
Turkey               9%
Mexico               9%
France               8%
Italy                8%
Pakistan             8%
Spain                8%
Philippines          8%
Egypt                7%
Malaysia             7%
Argentina            7%
Canada               7%
Thailand             7%
Ukraine              7%
Saudi Arabia         7%
Vietnam              7%
Bangladesh           6%
Colombia             6%
Poland               6%
Iran                 7%
Algeria              6%
South Korea          6%
Australia            6%
Netherlands          6%
South Africa         5%
Iraq                 6%
Japan                5%
Morocco              5%
Romania              4.9%
Peru                 4.6%
Taiwan               4.6%
Kazakhstan           4.5%
Chile                4.5%
Nigeria              4.5%
United Arab Emirate  4.5%
Israel               4.2%
Greece               4.2%
Venezuela            4.2%
Uzbekistan           4.1%
Portugal             4.0%
Belgium              3.9%
Czechia              3.9%
Singapore            3.8%
Hungary              3.8%
Azerbaijan           3.7%
Ecuador              3.6%
Yemen                3.5%
Sweden               3.4%
Austria              3.5%
Belarus              3.4%
Hong Kong            3.3%
Switzerland          3.2%
Jordan               3.2%
Bulgaria             3.2%
Dominican Republic   3.2%
Nepal                3.1%
Guatemala            3.1%
Myanmar              3.2%
Kenya                3.1%
Serbia               3.1%
Sri Lanka            2.9%
Tunisia              3.0%
Lebanon              3.0%
Bolivia              2.9%
Costa Rica           2.8%
New Zealand          2.6%
Ghana                2.6%
Ireland              2.6%
El Salvador          2.6%
Honduras             2.5%
Libya                2.7%
Uruguay              2.5%
Paraguay             2.3%
Kyrgyzstan           2.3%
Cambodia             2.3%
Norway               2.3%
Oman                 2.3%
Panama               2.2%
Nicaragua            2.2%
Georgia              2.0%
Senegal              1.7%
Palestine            1.8%
Laos                 1.5%

In contrast, world average ratings are available for about 55% of apps.

These are shown in all other countries. The largest of these are China, Ethiopia, Congo-Kinshasa, Tanzania, Uganda. They also include Denmark, Finland, Slovakia, Croatia, and other smaller European countries.

As you see, users from small "local rating countries" see ratings only for a fraction of the apps for which world average ratings are available.

And the apps with ratings available in these countries are also very few in comparison to those with ratings available in large countries.

This is an obvious problem for both users and developers.

(Well, it's an advantage for the big companies whose apps are so popular that they have local ratings in all countries.)

This is why App Finder now shows world average ratings (marked as grayed-out) for apps without country specific rating, and has the option to show the world average instead of or in addition to the local ratings, and allows to use them to filter and to sort.

Of course, local ratings for a larger country with your language may often be preferable to world average ratings (consider that apps often get unjustified bad reviews from people who only speak a language the app does not support).

Therefore, you can also easily change the search-country in App Finder. For example, if you are from New Zealand, you may set it to the United States to see ratings for over 7 times more apps than you’d see otherwise. Also note that the ratings will probably be more reliable, since they’re based on the opinion of a much larger number of users.

And if you're from a "world average country", you may select a large "local rating country" to see ratings that are more specific to your language.

Further new features

With this update, App Finder can also show two decimals for higher ratings (consider two apps rated 4.85 and 4.94 stars respectively, which are both rounded to 4.9 stars by Google Play).

Further, the number of downloads is now shown with two significant digits, with is quite an improvement over Google Play which rounds them to powers of ten times 1 or 5.

An Example

Below you see a list of apps in the Tools category with at least 10k downloads and at least 4.5 stars world average rating, ordered by release dated descending.

The big numbers are the world average ratings, below them the United States rating is shown if available.

You see that for these recently released apps, only for about half of them a US specific rating is available, even if they have already more than 10,000 downloads.

(For the UK it's even less of course, and for Australia for none of the first 50 apps in this list local rating is available.)

Also, the third app has a suspicious looking 5.00 US rating at a world average of only 4.56.

The screenshot also demonstrated App Finder's display of the download count with two significant digits.

Screenshot_20230512-004656.png
 

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Version 1.0.10: Links to the Google Play website are now available to see reviews in other languages

In addition to the links to the Play Store app, there are now links to open the Google Play details pages in a browser.

This makes it possible, for example, to change the language by appending &hl=xx to the URL, where xx is the language code, e.g. en for Englisch.

This way you can see reviews in different languages.

To activate the links, tap the cog-icon beside the Play Store link on a details page. There is also an option to set the language to English automatically.
 

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This post was improved significantly on June 22

Finding the best apps for a specific purpose with the Play Store and with App Finder: A detailed example

Summary:

With App Finder, it is much easier and faster to find the best apps for a certain purpose.

A detailed example of a search for advanced calculator apps is given, but the principles apply for all kinds of apps, like file managers, music players, and also games.

In this article, I consider the case where commonly used terms are available for the search (scientific calculator and graphing calculator in the example). The next article is concerned with the opposite case.

If you find anything wrong or incomprehensible, please let me know!



Specifically, the example will be scientific calculator apps that can also draw graphs.

Since scientific calculator and graphing calculator are universally used terms, we would expect every such app to have these terms in the description. Not necessarily both exact phrases, but forms of the words scientific, graphing, and calculator (maybe something like scientific calculations, and graphs of functions).

Since Google Play tries to understand the meaning of search queries, it should (and does) easily find apps where such variations of the query appear in the description.

This is similar with App Finder since it equates different forms of words (e.g., graph, graphs, graphing, and calculator, calculations).

So,

scientific graphing calculator

seems to be a good query for both Google Play and App Finder.

Search engines like the Play Store search and App Finder cannot measure the actual quality of apps of course, but only consider data like user rating and number of users. Therefore, we can compare the performance only by how well they sort the results based on these data and the relevance to the query.

However, at least for the apps relevant to this example, their overall quality seems to coincide quite well with the average user rating, as you will see from my comprehensive review of advanced Android calculator apps:

The following 7 apps performed best in my tests and also have some of the best user ratings (compared to other relevant apps), all at least 4.60 stars:
  • Hiper Calc
  • Scientific calculator Plus 991
  • Scientific Calculator 300 Plus
  • Graphing calculator plus 84 83
  • Graphing Calculator + Math
  • Scientific Calculator by Philip Stephens
  • Graphing Calculator - Algeo
(I have looked through hundreds of apps and reviewed 40 of them. About 80 features were checked, and the apps were tested with several more difficult test problems.)

(There are several other good advanced calculator apps, but those are not described as scientific graphing calculators by the developers, and thus cannot be expected to be returned with the above query.)

It follows that the ranking of the listed apps will be a good measure for the performance of the search engines.

As the only relevant filter that can be applied in Google Play is for 4.0 or 4.5 stars user rating, let us first compare the results of the above query with a 4.5+ star user rating filter.

As you see from the screenshots below, the apps from the list are in position 1, 2, 4, 5, 16, 25, 33 with Google Play, and in position 1, 2, 3, 7, 9, 12, and 31 with App Finder.

c1.jpg

So far it seems that App Finder and Google Play perform quite similar.

But now consider the filters available in App Finder. If we require the apps to be updated within the last year, and increase the user rating requirement to 4.60 stars, we get only 21 results. They still include all 7 apps from the list.

We can narrow the search further by requiring the word calculator to occur in title or summary. For this, we just have to put a + in front of it in the search query. Now we have 18 results total, and the apps from the list are in positions 1, 2, 4, 8, 10, 12, 16. This is an improvement of about factor 2 against the search with Google Play.

(We could refine the search further by requiring also on of the words scientific or graphing in title or summary by adding +scientific/graphing to the query, which would remove 2 more irrelevant apps.)

c2.jpg

If we wanted to find the very best apps as fast as possible, we could increase the user rating requirement further to 4.70 stars. With this filtering, we get only 12 results. We have only lost Algeo which is much less comprehensive and powerful that the others, and Plus 84 83, which is a variant of Plus 991.

c3.jpg

Finally, consider that App Finder can show additional data, short descriptions, and screenshots directly in the result list. This makes it clearly much easier and faster to discern low quality from high quality apps, and ones that you may like from ones that you won't:

Play store:
hp.jpg
App Finder:
hi.jpg

Note that App Finder adapts to phones and tablets of all sizes. Here's how the result list may look on a 10" tablet:

c4.jpg
 
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Finding apps with specific features with the Play Store and with App Finder: A detailed example

Summary:

With App Finder, it is much easier and faster to do a comprehensive search for apps with specific features.

While it is possible with the Play Store to do comprehensive and specific searches, the required queries are very long.

For queries that are probably used by most people, the Play Store may often return many irrelevant results before some of the best results.

This is a significant disadvantage for both users and developers of high-quality apps that are not very popular.

A detailed example of a search for advanced calculator apps is given, but the principles apply for all kinds of apps, like file managers, music players, and also games.


This article is quite long because I try to justify my statements quite rigorously.

If you find anything wrong or incomprehensible, please let me know!



The search in the last example was quite easy to do because there were universally used terms for the apps we were looking for (scientific calculator and graphing calculator).

However, you may sometimes need to search for apps with specific features, where such terms do not exist. Therefore, I will now show how the Play Store search and App Finder can be used in this case, and how they compare.

As an example, we will use calculator apps for advanced mathematics that can solve equations, calculate derivatives and integrals, draw graphs, etc.

As you will see, there are some very good such apps that are not called scientific calculator or graphing calculator by the developers. So this is a good example for a search where we must look for features mentioned in the description.

It is of course difficult to predict which features a developer would choose to include in the description, and what words would be used.

But if we only refer to functionality that is important and popular and consider alternative descriptions, we can expect to miss only few good apps.


For our example, equation solving, calculation of derivatives and integrals, and graphing seem to be such features that we can expect in the description of every app that has them.

We will start with the

Play Store search

A simple query that one might try first would be

(1) calculator equations derivatives integrals graphs

(calculator is important because we would else get many formularies, learning apps, etc.)

To make this example more overseeable, we limit it to apps with at least 4.5 stars user rating. With this filter, we get the following result list (only the beginning is shown):

1 p calculator equations derivatives integrals graphs.jpg

As you will see from my comprehensive review of advanced Android calculator apps, the following 13 apps (and probably very few others) have our desired features and a 4.5+ star user rating:
  • Hiper Calc
  • Scientific Calculator Plus 991
  • Graphing calculator plus 84 83
  • Scientific Calculator by Stephens
  • GeoGebra*
  • Graphing Calculator + Math
  • WolframAlpha*
  • Graphing Calculator – Algeo
  • Photomath*
  • Mathway*
  • HiEdu Scientific Calculator
  • TechCalc
  • Class Calc
(The apps with a star are not called scientific calculator or graphing calculator by the developers. Scientific Calculator 300 Plus from the last example has all desired features, but the description on Google Play is very short and does not state that it can calculate derivatives, so we cannot expect search engines to find it with our query, and I have omitted it from the list.)

In the results from the Play Store search above, they are in position 1, 3, 5, 6, 7, 8, 15, 16, 17, 19, 31, 41, 92 (not counting ads, and for apps with different versions only referring to the first occurrence).

While the beginning of the list looks good, two of the best apps (WolframAlpha and Scientific Calculator by Stephens) are in places 41 and 92, and most apps before them are not what we’re looking for.

For example: Desmos (on place 2) does not have the word integrals or anything similar in the description (and actually can’t calculate integrals). Derivative Calculator (on place 4) does not have the word equations or anything similar (and can’t solve equations). For about half of the apps in the list you will already from the title see that they’re what we’re looking for.

So, the Play Store search returns many apps where not all words from the query occur in the description.

To change this, we have to place the words in quotes. Then however, it does not look for variations of the words
:

With the query

(2) ”calculator” “equations” “derivatives” “integrals” “graphs”

we get only one app without all the words (Calculator Pro – All-in-one) and two spam apps (the last two), not counting ads. However, only 4 of the 13 apps from the above list are included:

2 q calculator equations derivatives integrals graphs.jpg

If we use the singulars of the words,

(3) ”calculator” “equation” “derivative” “integral” “graph”

we get 4 other apps from the above list:

3 q calculator equation derivative integral graph.jpg

If we combine the possibilities using the OR operator,

(4) “calculator” ("equations" OR "equation") ("derivatives" OR "derivative") (“integrals” OR “integral”) ("graphs" OR "graph")

we get 9 apps from our list and very few irrelevant apps:

4 q or.jpg

Interestingly, the parentheses in the above query are not necessary, without them we get exactly the same result. OR seems to be evaluated before the spaces denoting “and” by default, at least if quotes are used. Further, I have checked with several queries that parentheses are ignored.

The results from the last query show that we are on the right track for getting comprehensive and specific results.

However, we must consider many more possibilities: differentiation may be used instead of derivative, integration instead of integral, and graphing or plot instead of graph. Further, equation solving might be subsumed under algebra, and derivatives and integrals under calculus. Also, the app may not even be called calculator (e.g., WolframAlpha is called a tool for getting answers).

With all this, we arrive at

(5) ("equations" OR "equation" OR "algebra") ("derivatives" OR "derivative" OR "differentiation" OR “calculus”) (“integrals” OR “integral” OR "integration" OR “calculus”) ("graphs" OR "graph" OR "graphing" OR "plot")

Although this query is so long that probably no one would use it normally, the outcome is very good: In the total of 26 results, all 13 apps from the above list are included, and there are nearly no irrelevant results:

5 q all.jpg

I have also tried to simply list the terms from this query without quotes,

(6) equations algebra derivatives differentiate integrals integrate calculus graphs plot

but the outcome is not better than in the first query, and the app that was in place 92 there (Scientific Calculator by Stephens) is even further down the list if it is there at all:

6 p all.jpg

Finally, I have tried “natural language” queries:

(7) calculator apps for advanced mathematics

(8) apps that can solve equations, calculate derivative and integrals, and draw graphs

However, they do not work better.

The search on the Google Play website is worse. For query (1) we get 10 results total and only 5 relevant apps:

web1.jpg

For query (5) we also get 10 results and only 5 good apps.

Query (6) returns 30 apps total and 6 from the above list.

A Google web search with site: play.google.com does also not work better:

Query (1) returns 3 of the apps from the above list within the first 100 results (plus 2 relevant apps with less than 4.5 stars).

Query (5): 5 apps from the list plus 2 with less than 4.5 stars.

Query (5) with &lr=lang_en: 7 apps from the list plus 3 with less than 4.5 stars

Query (5) with “Verbatim”: 7 apps from the list plus 3 with less than 4.5 stars

An unrestricted Google web search for

(9) Android apps that can solve equations, calculate derivative and integrals, and draw graphs

Returns only few Google Play pages, and articles which do not give a good overview of the relevant apps.

All this shows the advantages of a well-considered keyword search (query 5) over semantic search as it is currently implemented by Google.
 

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continuation of the previous post

App Finder

App Finder uses keyword search by default (and currently it cannot do semantic searches).

If just words separated by spaces are entered (and no search operators like OR), it returns exactly those apps where all the words, or forms of them, occur in the description (or title or developer name).

Thus, we don’t have to use quotes in this case, and don’t have to care about different forms of words.

(Quotes are used to search for sequences of words in App Finder. While App Finder equates all relevant forms of the words from this example, it is of course not always clear what counts as a form of a word. Currently, PostgreSQL’s default dictionary is used for word normalization, which does not seem to be optimal.)

Therefore, the considerations before query (5) above lead to the following query (in common search language)

(10) (equation OR algebra) AND ((derive OR differentiate) AND integrate OR calculus) AND (graph OR plot)

(where AND is evaluated before OR in the absence of parentheses)

While App Finder does understand this query, it can be written shorter using the alternative “or” operator / that is evaluated before “and”:

(11) equation/algebra (derive/differentiate integrate OR calculus) graph/plot

Filtering for 4.5+ stars user rating, this query gives 33 results, and all apps from the above list are included within the first 24:

a1.jpg

Nearly all non-calculator apps can be removed by disallowing the words learn, tutor, and formula in title or summary by adding -+learn/tutor/formula to the query (which however also removes the "learning calculator" HiEdu):

a2.jpg
 
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Introductory prices end today!

Today is the last chance to get a Plus licence at the reduced price of $9 per year / $24 for ever.

(Standard prices: $12 per year / $36 for ever)

Your purchase would contribute to the operation and improvement of App Finder.
  • See the list of upcoming features in the first post.
  • Note that the operation is quite expensive, especially since Google does not provide an API, and the data thus need to be scraped regularly (A page for each about 2.4 million apps for 180 countries = 430 million pages, plus more pages do discover new apps, which is about 73 TB of data. Further, a high-performance database server is needed to handle the search queries).
 

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Version 1.0.11: Devices without Google Play services are now supported

If the Play Store app is not available, the app links will be opened in another installed app store.

If Play Billing is not available, the Plus features are free for now!
 

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Version 1.0.12: Saving results as spreadsheet, larger font on phones possible
  • The results can now be saved as spreadsheet again (see the disk-icon below the filters).
  • 1-pane landscape layout is now supported for larger font on phones.
 

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The number of apps could be increased to 2,500,000+ (2,140,000+ available in the US).

This is already near to AppBrain (2,640,000+, see here).
 

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The features and advantages of App Finder

Our website is now online with
  • a detailed overview of the features and advantages,
  • a detailed comparison of the Play Store search with the free and paid version of App Finder,
  • and more.
We apologize that the site is not mobile-friendly currently, this will be changed soon.

While you need to read the complete features page to see the full value of App Finder, here are some highlights:
  • Advanced keyword search
    Together with other features, this makes it possible to do comprehensive searches in short time, so that the best apps can be found even if they are not very popular, and if the developers don’t have a high advertising budget.
  • Screenshots in the result list
    Obviously, this can help you to discern promising apps much faster.
    Apple's App Store has it. Now Android users have it too, and much better: Scrollable, scalable, and hideable.
  • Ads, in-app purchases, update date: Information in the result list and filters
    No explanation needed.
  • User ratings for about 2.8 to 38 times more apps than in Google Play* (in most of the world)
    This is due to the Play Store only showing local ratings in most larger countries. See the features page for more explanation. Obviously, this may be a huge benefit especially for users in small “local-rating countries”, and for independent developers.
* You can check this if you make a rather specific query (e.g., using a phrase in quotes) in both the Play Store and App Finder (with the Primary rating set to World average in the User rating options), and apply the 4.5+ star filter.


I'd like to use this occasion to explain that

App Finder needs your support​

Not much, just a little bit.

Consider that the essential functionality is free and without ads, see the comparison.

While some people seem to be angry that not more or even everything is free, most “serious users” (> 2 hours usage time in the last month) seem to be happy with the free features, as they didn’t even activate a free trial.

While I consider requiring payment for some more features, I intend to keep the essential features free and without ads.

However, the operation of App Finder is quite expensive, especially since Google does not provide an API, and the data thus need to be scraped regularly: A page for each about 2.5 million apps for 180 countries = 450 million pages, plus more pages do discover new apps, which is about 75 TB of data. Further, a high-performance database server is needed to handle the search queries.

Obviously, the creation of App Finder required time and effort, and so will the improvement.

While I am confident that App Finder will soon get many more users when we start promoting it, this may take some time, and currently the revenues are only a fraction of the expenses.

So, if you wish App Finder to be continued and didn't do so already, please consider a little contribution:
  • Giving it a fair review on Google Play
    (People who don’t like it for whatever reason seem to be quick to give a 1-star rating)
  • Telling friends who might be interested
    (We’ll set up Facebook and Twitter soon)
  • Buying a Plus license, if only 1 week for $1, or 1 month for $2
    (More would help us in this starting phase and may save you money in the long run)
This will help us to
  • Continue the operation
  • Scrape Google Play more frequently
  • Implement new features that require more resources, like support for many languages, indexing of alternative app stores, search for exact words and synonyms, and possibly scanning of APKs
  • Gain more users through advertisement, so that innovative apps by independent developers will be found by more people, and so that the operation becomes more economical

i0l.jpg
 

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Version 1.0.14:
  • Keywords are now highlighted in the summaries on the result list also
  • Lists of the global and all local user ratings are now available (tap the rating in the result list)
  • There are now search operators for app name and developer name:
    • # searches for app name by prefix, e.g. #whats
    • @ searches for developer name by prefix, e.g. @skyi
    • Parentheses must be used if the search terms include spaces, e.g. #(app f)
    • Quotes can be used to require exact match (up to capitalization) instead of prefix match, e.g. @”skype”
 

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How App Finder may benefit app developers

The Play Store makes it very hard for less popular apps to be discovered

With billions of users, Google Play has a huge potential for app developers. However, its search and explore features benefit almost exclusively already popular apps, and apps for which developers pay advertisements.

Other apps are very difficult to find, even if they are high quality, highly useful, innovative, or have unique features. This is an obvious problem for both many developers and many users.

Some problems with the Play Store search are:
  1. It strongly prefers popularity over query match.
    If not forced to keyword search by using quotes, it often does not return less popular relevant results, or returns them only after many popular but irrelevant results.
    See the next post for examples.
  2. In most of the world, it shows local ratings only, which are available for just about 1.5% – 20% of apps, while global ratings are available for about 55% of apps. When users filter for 4 or 4.5 stars, apps without local rating are hidden.
    See here for further explanation.
  3. The result list is uninformative and uninteresting, so that it can be expected that users generally give up early and just decide for one of the first results.
    Further shortcomings are that the result count is not given, that the results are not numbered, that there are no systematic sort options, and that the search terms are not highlighted.

App Finder solves these issues and makes a better search available to everyone
  1. App Finder makes it easy to find all relevant apps:
    • It uses keyword search by default and returns only apps where every keyword is matched in the app description. By adding keywords, it is easy to make the query more specific. AI-based semantic search is planned as an alternative.
    • Further, there are many filters to refine the search without losing less popular apps, and there are sort options for average user rating and release date.
    • This often makes it possible to reduce the result count until all results can quickly be examined.
    • It is also possible to filter for few user ratings, and to sort the results by number of ratings ascending. While most people probably will not use these options, some do look for “hidden gems”.
    • See the next post for examples
  2. App Finder shows global ratings for apps without local ratings
    • Also, it has the option to use global ratings for the rating filter.
    • Further, users from small countries may choose to see ratings from a large country of their choice (note that there are ratings for about 8 times more apps for the US than for New Zealand, for example).
    • See here for further explanation.
  3. App Finder’s result list highly informative and engaging,
    • Systematic sort options, result count, result numbering, and keyword highlight provide orientation.
    • While we don’t have a comparison with the Play Store, App Finder’s users do scroll much: Of the about 60,000 queries that App Finder received in the last 6 months, the result list was scrolled about 9500 times over 30 results, 2400 times over 80 results, 830 times over 180 results, and 100 times over 380 results.

App Finder has the potential to reach the widest possible audience
  • The core functionality is available for free and without ads.
  • It has local prices, age ratings, and user ratings for all 200+ counties / regions supported by Google Play. Support for many languages will be added soon.
  • It is available on Google Play and as APK with a very small download size. Devices without Play Store and Google Play services are supported.
  • It is optimized for phones and tablets of all sizes, and for older and slower devices and slow connections.
  • It requires no sign-in, does not collect personal data, does not share user data with third parties, requires minimal permissions, and includes very little 3rd-party code.
  • It is designed to be easy and intuitive to use and includes a complete user guide and other help.
  • A web interface will be available soon.

App Finder can help developers to analyze the market and the competition
  • The advanced keyword search, many filters, and the highly informative result list provide a significant advantage for this.
  • It has information not accessible on Google Play: User ratings with two decimals, lists of the global and all local ratings and rating distributions, and the exact download count.
  • Result lists with thousands of apps can easily be exported as CSV for further analysis.

App Finder facilitates the creation of comprehensive comparative app reviews
  • Most app reviews on the web do not provide a comprehensive objective overview of best apps.
  • This is an obvious problem for users.
  • But it is also especially a problem for independent developers of innovative high-quality apps.
  • App Finder is highly useful for the creation of thorough reviews. See this review of advanced Android calculator apps, which includes many excellent little-known apps from independent developers.
 

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Version 1.0.15: Play Pass and target API
  • There is now a filter for Play Pass apps and games. These are also marked in the result list (when the filter is applied, this redundant information is not shown).
  • There is now a filter for the target API available, and an option to show the target API in the result list.

We have 249 Play Pass apps and 1010 Play Pass games available in the US!
 

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Version 1.0.15a:

App Finder is now on
X (Twitter), Facebook, and Threads!
  • You’ll find the links also in the Help-menu, which has been restructured.
    .
    Important improvements are in development and will be announced there when they will be rolled out over the coming months, for example a web interface, indexing of alternative apps stores, indexing of iOS apps, support for other languages, search history, and creation of custom app lists.
    .
  • The user guide and other help has been improved and updated with the latest features.
    .
  • In Supporting App Finder from the Help-menu, you now find information about the objectives of App Finder.
    .
  • The Ads label is now shown in black instead of red, we think that this is more appropriate as there are many high-quality apps that contain ads which can be disabled with in-app purchases.
 

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The Problems with the Play Store Search and the Advantages of App Finder

Summary: While the Play Store search works well for finding apps by name or developer, it makes it difficult to find the best apps for a specific purpose, or apps with specific features.

Without using quotes, it is highly unreliable and often does not return some of the best and most relevant apps, or returns them only after tens or hundreds of irrelevant apps.

Using quoted words often leads to significantly better results. However, different forms of words and synonyms must be included in this case and combined with the OR operator, which leads to unnecessarily complicated queries.

These are serious problems, as many people may not think of using quotes, or of combining different word forms with the OR operator, especially since all this is undocumented.

With App Finder’s advanced keyword search, finding good apps is significantly easier, faster, and more reliable.

Quotes are not generally needed to get good results, and different word forms are searched automatically.

Additional advantages include special search operators, keyword highlighting, many filters, systematic sort options, display of the exact result count, and a highly informative result list with short descriptions and scalable screenshots.

In this article, the results from various searches with the Play Store and with App Finder are analyzed in detail to demonstrate these things.



Searching with the Play Store

Suppose we want to find the best calculator apps that can draw 3D graphs. This will be the main example in this article.

A natural language query

Since Google indicates for the web search that it understands simple questions in natural language (see here), many people might try a query like
calculator apps that can draw 3d graphs

However, you will see that

the Play Store search does not seem to understand this.

Without filters, the above query gives about 240 results.

Note that the Play Store slightly varies the results with each query and also “personalizes” them (see here), so you may get somewhat different results.

Of the first 10 results, the last 6 are clearly irrelevant as the apps cannot draw 3d graphs and the descriptions also do not state this (for number 5 to 9, the word 3d or something similar does not even occur, for the last one, the word graph or something similar does not occur).

Of the next 10 results, 8 are clearly irrelevant as you can check.

(The ads are also irrelevant, and I have excluded them from the counting.)


Evaluation of the results

While the number of clearly irrelevant results that are returned is already an indication for the quality of a search engine, the ranking of the actually best and most relevant objects seems to be the most significant measure.

More exactly: The ranking of the objects that would seem the best and most relevant from the information that the search engine possesses, in this case mainly the app descriptions, user ratings, and number of ratings and downloads.

Therefore, I have tried to find all apps with a good user rating (4.5+ stars) or high popularity (100k+ downloads), where the description indicates that they are what we’re looking for in this example (i.e., calculator apps that can draw 3D graphs).

For this, I have examined the results from multiple searches with both the Play Store and App Finder (the ones described in this article and some others), and also used the findings from my comprehensive review of advanced Android calculator apps.

I have found that the following 17 apps (and probably very few others) meet the above criteria:
  • GeoGebra 3D Calculator / Calculator Suite
  • Scientific Calculator / Pro (by Philip Stephens)
  • Graphing Calculator + Math/ Pro,
  • HiperScientific Calculator / Hiper Calc Pro,
  • Maple Calculator
  • TechCalc / TechCalc+,
  • microMathematics Plus
  • Visual Math 4D
  • Mathematics (by daboApps)
  • Calculator++
  • Grapher / Pro - Equation Plotter
(Apps that are not compatible with current Android devices are excluded.)


Back to the natural language query

You can check that of the 17 apps from the list above, only 5 occur in the first 50 results.

Scientific Calculator by Philip Stephens is at position ~215, after very many completely irrelevant apps, even though the description indicates that it is a calculator app that can draw 3D graphs and it is quite popular and has a fair rating.

One of the best-rated relevant apps (Scientific Calculator Pro by Philip Stephens) is not returned at all.

You see that

with natural language queries, you may miss most of the best apps.


A simple query

Let us now try a simple query with just the decisive words:
calculator 3d graphs

This does not work significantly better:

There are now 4 clearly irrelevant apps in the first 10 results (Graphing calculator plus 84 84, Desmos Graphing calculator, and Graphing calculator (X84) cannot draw 3d graphs, and actually don’t have the word 3d in the description. clkGraphs 3D is not a calculator and doesn’t have the word calculator in the description).

Of the next 10 results, 8 are irrelevant again.

Of the apps from our list, 7 are within the first 50 results. Scientific Calculator by Philip Stephens is at position ~190, results, Scientific Calculator Pro is again not returned .


A look at the sort order

Let us compare 3 apps from the result list: Scientific Calculator, Scientific Calculator Pro, and Graph Plotter, all by Philip Stephens.

The first two have all keywords from the query in the description (and are actually good calculators with good 3D graphing), good to very good user rating, and the first one is also quite popular.

The third one does not have the word calculator in the description (and actually includes only the graphing functionality of Scientific Calculator but not the calculation functionality), has a really bad rating, and is not very popular.

However, the first one is at position ~190, the second one is not returned at all, and the third one in position 33!

Scientific CalculatorScientific Calculator ProGraph Plotter
Description includes all words from the query?YesYesNo
User Rating4.24.72.9
Number of ratings5600140130
Number of downloads1.3M1.5k58k
Position in the result list~190not returned33

It would be acceptable if the Play Store would return some low-rated and less relevant apps early in the result list. The big problem is that

highly relevant apps with good to very good user rating are virtually undiscoverable with a reasonable query.
 

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Using quotes

The obvious problem with the previous two queries was that the Play Store returned mostly apps where decisive words from the query did not occur, for whatever reason.

With Google’s web search, quoting words requires them to actually occur (and in the same exact form), so we can expect that this will help.

(Note that the + operator that seemed to work in Google web search in the past to require words to actually occur does not work in the Play Store)

Let us first try to simply put all words from the last query in quotes:
“calculator” “3d” “graphs”

The results show that we are on the right track:
  • There are no irrelevant apps in the first 10 results, and 2 in the next 10.
  • There are only 37 results total, and 11 of the 17 apps from the list above are included.
The main reason that apps from the list are missing is that quotes request the exact words, while some apps from the list do not contain the exact word graphs.

Before we come to this, note the following:
  • GeoGebra Calculator Suite is not returned although it does have all exact words in the description.
  • As noted, there are 2 irrelevant apps in the first 20 results (Weight Loss for Women and Air Navigation Pro). While the first one coincidentally contains the words calculator, 3D, and graphs, the second one does not have calculator in the description. Several other apps further down the list also do not contain all keywords (e.g., 11+ Math), and some do not even contain any keyword (Fox 7 Austin: News)
We see that

Even with quotes, the Play Store search cannot be trusted to return all apps where all keywords occur.

Further, it returns many apps where the keywords do not all occur. Some are completely unrelated to the query.



Using the OR operator


Let us now improve the query to include other word forms and synonyms.

It seems very likely that calculator and 3d occur in these exact forms for all relevant apps (up to capitalization, which is ignored by the Play Store even if quotes are used).

However, we should expect graph or graphing instead of graphs, and synonyms like plot or plots. We can cover these cases with the query
“calculator” “3d” “graph” OR “graphs” OR “graphing” OR “plot” OR “plots”

Conveniently but maybe unexpectedly, the OR operator is evaluated before the spaces denoting AND, that is, the above query is evaluated as

calculator” “3d” (“graph” OR “graphs” OR “graphing” OR “plot” OR “plots”)

(Note that parentheses in queries are ignored by the Play Store search.)

With this query, there are about 110 results total, and 15 of the 17 apps from the above list are included (all within the first 48 results).

Mathematics by daboApps and Calculator++ are missing, despite having the exact words calculator, 3d and plot in the description. The reason seems to be that Google hides these apps from searches because they don’t comply with some policies, so this is not a problem with the search engine.

Note that there are again very many apps returned where not all required words from the query occur.

Nevertheless, we have seen that

the Play Store search may work far better with quotes than without.


Using filters


Let’s now suppose that we want to find the probably best apps as fast as possible.

The only help that the Play Store offers for this is the 4.0 / 4.5 star filter.

If we apply the 4.5-star filter with the “simple query” above, the results are not better than without the filter:

The total number of results is about the same, and the irrelevant apps with less than 4.5 stars are just replaced by other irrelevant apps with 4.5+ stars.

Of the 10 apps from our list that have 4.5+ stars and are not hidden deliberately (see above), 4 are in the first 20 results, and 5 in the first 50.

If we apply the 4.5-star filter with the query using quotes and OR, the results are quite good:

There are a total of 30 results, all 10 of the 10 qualifying apps from the list are there, 8 in the first 10 results.

However, there are still many irrelevant apps included, some of which do not contain all required words from the query.
 

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