The security and privacy of Tella users is at the core of our mission. It is therefore natural for the application's code to be entirely open-source. This means that it is publicly available for review: anyone can audit our code to verify that we don't misuse user data, that we actually do what we say, and that our code is robust.
Tella's code for both Android and iOS can be accessed here on our GitHub repository. Rather than trust us, you can audit the code yourself or ask someone you trust to do it, or read the reports that independent security firms wrote after auditing Tella’s code.
We also publish and maintain a Free and Open Source version (FOSS) of Tella for Android, which doesn't contain any closed-source or proprietary library or dependency. The code is shared across all Android's version of Tella and we generate the FOSS or regular Android Tella using product flavors at build time. When possible, we use FOSS libraries and dependencies for both versions of Tella Android. The FOSS version of Tella Android is available on the F-droid store.
A detailed list of features available on each platform is available here:
| Feature | Android | iOS | Android FOSS |
|---|
| App Lock | Password, PIN, Pattern | Password, PIN | Password, PIN, Pattern |
| Background encryption | ✔️ | ✔️ | ✔️ |
| Backups (to another Tella or to a server) | ✔️ | ✔️ | ✔️ |
| Lock timeout configuration | ✔️ | ✔️ | ✔️ |
| Camera silent mode | ✔️ | Not yet | ✔️ |
| Screen Security | ✔️ | ✔️ | ✔️ |
| Restrict unlocking attempts | ✔️ | ✔️ | ✔️ |
| Edit Media | Crop, Rotate, Flip and Zoom Photos | Crop and Rotate Photos, Trim Audio and Videos, Rotate Video | Crop, Rotate, Flip and Zoom Photos |
| Encryption | ✔️ | ✔️ | ✔️ |
| Encrypted file management | ✔️ | ✔️ | ✔️ |
| Feedback | ✔️ | ✔️ | ✔️ |
| Import files from device | ✔️ | ✔️ | ✔️ |
| Preserve metadata when importing | ✔️ | ✔️ | ✔️ |
| Privacy preserving analytics (opt-in) | ✔️ | Not yet | ✔️ |
| Camouflage | ✔️ | Not possible in iOS | ✔️ |
| Homescreen customization | ✔️ | ✔️ | ✔️ |
| Camera (photos and videos) | ✔️ | ✔️ | ✔️ |
| Select video resolution | ✔️ | Not yet | ✔️ |
| Audio Recorder | ✔️ | ✔️ | ✔️ |
| Open files in Tella | ✔️ | ✔️ | ✔️ |
| Verification mode | ✔️ | Not yet | ✔️ |
| Quick delete | Files, Connections and Tella | Files and Connections | Files, Connections and Tella |
| Quick exit | Locks and close | Locks | Locks and close |
| Share button | ✔️ | ✔️ | ✔️ |
| Server connections | - Tella Web
- Uwazi
- Google Drive
- Dropbox
- Nextcloud
- Open Data Kit (Forms) | - Tella Web
- Uwazi
- Google Drive
- Dropbox
- Nextcloud | - Tella Web
- Uwazi
- Open Data Kit (Forms) |
| Nearby Sharing | ✔️ | ✔️ | ✔️ |
| Offline data collection | ✔️ | ✔️ | ✔️ |