Welcome to Android Central! Which phone? ThinkFree is a mobile office suite, so the Viewer is probably an app that allows you to view a document (but not edit it). It might be a "lite" version that's included with your phone, which might then encourage you to purchase the full suite. https://forums.androidcentral.com/e...com.tf.thinkdroid.zimbra&hl=en&token=-im8n6oN