Skip to main content



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 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 at

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?

App LockPassword, PIN, PatternPassword, PIN
Lock timeout configuration✔️✔️
Camera silent mode✔️Not yet
Screen Security- screenshots
- screen recordings
- app preview
- screen recordings
- app preview
Encrypted file management✔️✔️
Import files from device✔️✔️
Camouflage✔️Not possible in iOS
Homescreen customization✔️✔️
Camera (photos and videos)✔️✔️
Select video resolution✔️Not yet
Audio Recorder✔️✔️
Open files in TellaPhotos, videos, audioPhotos, videos, audio, PDF
Verification mode✔️Not yet
Quick delete✔️✔️
Quick exit✔️✔️
Connections to collect data and send files- Tella Web
- Uwazi
- Open Data Kit (Forms)
- Tella Web
Offline data collection✔️✔️

For more details about each feature see Features .

Is Tella available on desktop?

As of November 2022, we are in the process of developing Tella Web, a web app that acts as a repository to store reports submitted by Tella users, include photos, videos, and audio, and the verification information attached to those. We expect to release Tella Web in January 2023. In following versions, it will also be possible to use Tella Web to manage Tella users and customize how Tella looks on Android and iOS devices.


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 will be one of the options available to collect data from Tella see connections

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.

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 priority, so we work hard to make Tella available in languages spoken by communities who express the need for Tella.

Currently Tella is available in:

  • Arabic
  • Belarusian
  • Burmese
  • English
  • Indonesian
  • Jingpho
  • Kannada
  • Karen Sgaw
  • Malayalam
  • Portuguese
  • Russian
  • Spanish (Latin America)
  • Tamil

We, however, don't always have the capacity or resources to keep all translations up to date. If you wish to contribute to the translation of Tella, join us here. If you want us to add a new language, email us, and we'll do our best to add it.

Does Tella work on tablets?

Tella works on Android tablets.

It is currently not available on iPad. Please email usif 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! You can share any suggestion, idea or feedback at


How much storage do I need to install Tella?

The Tella app itself is small:

  • 19MB 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 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

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 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: