Etopa is a two-factor-authentication app, which runs as a web server and can be accessed using a web browser or using an Android app. I would consider it stable to use, but there are still many functions to yet be implemented.

You can use the Etopa.de instance or host your own.

F-Droid: Add repository https://fdroid.ltheinrich.de and search for Etopa (fingerprint B90FC7691EC5BE977DCBBCB18C3984C794CCAFA5BB8712ED2D64F9FD8703B636)

Google Play Store: Etopa 2FA

Amazon Appstore: Etopa

Samsung Galaxy Store: Etopa

Clone repo

git clone https://ltheinrich.de/etopa && cd etopa

Configure

./configure

Build

DEBUG_SIGN=y make

API server: target/build/etopa

Android APK: target/build/etopa.apk

Web archive: target/build/etopa.tar.xz