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Frequently asked questions about Tella


What is Tella?

In challenging environments, with limited or no internet connectivity or in the face of repression, Tella is an app that makes it easier and safer to document human rights violations and collect data.

For more information on how to use Tella, visit the Getting Started guide.

Who makes Tella?

Tella is developed and maintained by Horizontal, a human rights non-profit. In addition to developing Tella, Horizontal develops other privacy and security tools, and trains activists, journalists, and human rights defenders in digital security.

Is Tella available on Android?

Yes, Tella is available for Android and can be downloaded directly from the Google Play Store , from our Telegram channel or from this folder, as an APK, to be installed manually. If you need to help to install the app manually you can follow this guide or contact us.

Is Tella available on F-Droid?

Yes, we published a version of Tella Android on F-Droid, which we call Tella-FOSS. On this version, all features are available except for:

  • Tella Web Connection
  • Option to delete original file when importing
  • Some of the Camera’s features (zoom, flip camera, enable flash, enable grid, change video resolution)

This version is fully open source, which means that all code of Tella and the code of all libraries that Tella uses are fully free and open source.

This version does not contain any trackers, not even the ones which help us detect bugs and crashes on Android.

Is Tella available on iOS?

Yes, Tella for iOS can be downloaded from the App Store. Tella for iOS is in an earlier stage of development, so not all features are available yet. However, it is stable and has undergone a security audit.

For details about which features are available for iOS, see What features are available on each platform.

What features are available on each platform?

FeatureAndroidiOSAndroid FOSS
App LockPassword, PIN, PatternPassword, PINPassword, PIN, Pattern
Background encryption✔️✔️Not yet
Lock timeout configuration✔️✔️✔️
Camera silent mode✔️Not yet✔️
Screen Security✔️✔️✔️
Restrict unlocking attempts✔️✔️Not yet
Edit MediaCrop and Rotate PhotosCrop and Rotate PhotosNot yet
Encrypted file management✔️✔️✔️
Feedback✔️✔️Not yet
Import files from device✔️✔️Yes but missing delete original file
Preserve metadata when importing✔️✔️Not yet
Camouflage✔️Not possible in iOS✔️
Homescreen customization✔️✔️✔️
Camera (photos and videos)✔️✔️Yes but missing zoom, flip camera, enable flash and enable grid
Select video resolution✔️Not yetNot yet
Audio Recorder✔️✔️✔️
Open files in Tella✔️✔️Photos, videos, audio (not PDF)
Verification mode✔️Not yet✔️
Quick deleteFiles, Connections and TellaFiles and ConnectionsFiles, Connections and Tella
Quick exitLocks and closeLocksLocks and close
Connections to collect data and send files- Tella Web
- Uwazi
- Open Data Kit (Forms)
- Tella Web
- Uwazi
- Uwazi
- Open Data Kit (Forms)
Offline data collection✔️✔️✔️

For more details about each feature see Features.

Is Tella available on desktop?

Tella Web is a web app that acts as a repository to store reports submitted by Tella users, including photos, videos, and audio. Learn more about Tella Web here


Note that it is not possible to encrypt and hide files or create reports on Tella Web. These features are only available on the mobile apps. Tella Web is one of the connections available to send the data collected on the Tella app.

Where can I get Tella?

Please refer to the Is Tella available on Android?or to the Is Tella available on iOS? questions depending on the device you own.

What phones support Tella?

Tella is compatible with devices running Android 5.0 or later and iOS 14.0 or later.

Is Tella free?

Yes, Tella is free to download and use. It will remain free forever.

Tella is also Open Source.

What languages is Tella available in?

Language accessibility is one of our priorities, so we work hard to make Tella available in languages spoken by communities who express the need for Tella.

Currently Tella is available in:

  1. Arabic
  2. Belarusian
  3. Burmese
  4. English
  5. Indonesian
  6. Jingpho
  7. Kannada
  8. Karen Sgaw
  9. Kurdish
  10. Malayalam
  11. Persian
  12. Portuguese
  13. Russian
  14. Spanish (Latin America)
  15. Tamil

Read more about Language accessibility in Tella here.

Does Tella work on tablets?

Tella works on Android tablets, but it is currently not available on iPad. Please contact us if iPad support is important to you so that we can make it a priority.

Where can I send my suggestions to improve Tella?

We'd love to hear from you! Please contact us!


How much storage do I need to install Tella?

The Tella app itself is small:

  • 26MB on Android
  • 7MB on iOS

The app size will grow depending on the size of the data stored on it. There is an option to configure the quality of the videos taken with Tella (Very high, High, Medium or Low) if users needs to save space. It's also possible to delete the files, photos and videos in Tella to save space.

How much can I store in Tella? What is the storage limit?

There is no specific storage limit for Tella, limits will depend on the system storage space available in your device.

External storage locations (like SD cards) are not currently used by Tella.

Security & Privacy

I can't remember my lock. How can I get into Tella?

Unfortunately there is no way of getting into Tella if you forgot your lock. You will have to uninstall Tella and reinstall it. There is no way of retrieving the files that were stored in Tella.


Learn more about Tella Locks in our video tutorials.

How do I migrate Tella to a new phone?

Unfortunately there is no way to automatically move your files and data from Tella on an old phone to Tella on a new phone.

Using Apple's Migration Assistant will not work: your files will be moved to the new phone encrypted, but not your encryption keys. As a result, you will not be able to decrypt and open these files.

In order to migrate your Tella files to a new phone, you need to install Tella on the new device, export all files out of Tella, and import those to the new phone manually. We recommend following these steps:

  1. On your old phone go to the "All Files" folder and use the "Select all" checkbox to select all your files and folders. Keep in mind that the files will remain visible -unencrypted-, on the phone galery.
  2. Use Quick Share (in Android), Airdrop (in iOS) or any other data transfer utility to move your files to the new device. Files will be tranfered unencrypted.
  3. On your new phone open Tella and go to the "All Files" folder, tap the "+"" button, and select "Import from device". You can choose "Delete orginal" in the dialog to make sure the files are only stored safely inside Tella. Select the files you had just exported from your old phone to import them to Tella.
  4. Make sure you delete the files that are not secured in Tella's encrypted vault from both your phones' galeries.

How secure is Tella?

There is no such thing as an app that is 100% "secure". Security is dependent on the threats and risks faced by each user. With this in mind, we built Tella to protect users from device searches (at checkpoints, borders, in the street, etc) and to protect sensitive files and data, both on the device and when they send them.

To do this, Tella encrypts all data in the user's device, locks using password protections, and can be hidden with a variety of camouflage options. It also encrypts all data that is sent to servers. You can read details about how do we do this, and some risks and limitations on the Security & privacy section of Tella's.

Has Tella undergone security audits?

Yes! You can see all our security audits here.

Deploying Tella

What does it mean to "deploy" Tella?

Deploying Tella means getting Tella ready to use for your specific context and among your community or organization. This might include:

  • assessing where your data will live (for example using a third party server or self-hosting it)
  • deciding how are you going to structure your data
  • installing and configuring the server
  • training users and helping them get the app installed and configured
  • planning for maintenance of the server

Please go to the For Organizations section to read more about deploying Tella.

Can you help me deploy Tella?

Yes, we'd love to! Tell us about what you want to use Tella for and in what context you want to deploy it contact us and we'll get in touch.

How is Tella different from other documentation apps?

We want to help you understand if Tella is the best app for your specific context. There are other documentation apps developed by other organizations and human rights defenders that you might consider as well.


We created this comparison table to help you understand the difference between Tella and other apps available, but of course, we may be biased 😊. For comparisons by independent organizations, have a look at the links below.

TellaODK Collect
EyeWitness to AtrocitiesCameraVProofMode
On-device encryption
Verifiable evidence
Data-collection (data is sent to, and stored on, a remote server)
Customizable forms
Self-host option (full control over data)
Advocacy or legal support

Some research and reflections about Tella--and the human rights documentation process in general--can be found here: