Tella is a free, open source, and multilingual application designed for journalists and civil society experiencing authoritarian censorship and surveillance to securely collect and store critical data.
We conducted a comprehensive security assessment of Tella between September and November 2025. Auditors focused on Tella’s core protection mechanisms across three priority tiers:

1. The new Nearby Sharing feature, the tool’s data protection architecture, authentication systems, and application masking features.
2. Platform-specific security reviews across Android, iOS, and desktop codebases, including the security of their server integration with other cloud storage platforms. This tier also entailed the development of comprehensive threat modelling for civil society and journalist use cases.
3. Code analyses to ensure that code quality and security-by-design principles are present throughout the app.

Tella developers reviewed the findings and carried out a coordinated remediation effort across the Android, iOS, and desktop codebases. Auditors conducted a final fix-verification round in June 2026 against Tella iOS 3.1.0, Tella Android 3.2.0, and internal desktop builds.

After extensive code review, testing, retesting, remediation, and fix verification, auditors found that Tella’s overall security posture delivers the level of protection required for its user base.