An overview of Tella’s features and capabilities.


Tella was designed from the ground up to fit the needs of those who face high risks of repression because of their work or their identity.
Encryption by default
All the data contained in Tella is encrypted by default. Without the user's lock, it cannot be accessed by anyone.
Tella can be hidden on the user's phone to minimize the risks of discovery by repressive forces.
Emergency delete
In just a few seconds, the user can delete all the data contained in Tella, including the app itself.


With Tella, individuals and groups are empowered to safely documents events around them, whether that’s human rights violations, violence, or electoral fraud.

Customizable forms

Collect the specific data you need with over a dozen different question types (text, multiple choice, geolocation, etc), conditional logic, and data validation. 

Verifiable evidence

Optionally, Tella can collect information about the user's device, network, and location to help researchers, lawyers, or journalists verify the origin of photos, videos, and audio recordings.

Offline mode

With poor connectivity or no internet at all, fill as many forms as needed, save them in Tella's encrypted storage, and send after reaching a reliable connection. 


Tella is based on the Open Data Kit (ODK), an open standard with dozens of tools to choose from to create forms, manage users, and visualize the data collected. 


Tella is designed for those whose safety is at risk, so it is free to download and use, and it will remain free forever.
Open source
The code for Tella is publicly available so that researchers, security analysts, and developers can freely audit and reuse it.

Something is missing? Do you have ideas or suggestions to improve Tella? We want to hear from you!

Tella is a project of Horizontal, a nonprofit organization serving frontline defenders, activists and journalists through digital security support and tool development.

Get it on Google Play