BetaScout
Find and track Google Play beta programs for your installed apps
...If you sign in, BetaScout reads your own testing pages to detect your memberships and whether each program is open or full. It never joins a program on your behalf.
There is no telemetry and no analytics; your app list and markings stay on the device. Available in English, Finnish, Spanish, German, French, Italian and Brazilian Portuguese.
Source code, issues and discussions: https://github.com/jrs8205/BetaScout