Convocation Research + Design conducted a comprehensive security assessment of Horizontal’s Tella application, an open-source application that helps journalists and civil society safely collect and store sensitive information in high-risk environments developed by Horizontal. The audit examined Tella’s Android, iOS and desktop applications, including encryption, authentication, data protection, its new Nearby Sharing feature, and integrations with external platforms. Following remediation by the Tella development team, Convocation conducted a follow-up verification in June 2026 to assess fixes and confirm improvements to the application’s security.

Security Researchers: Sam Smith, Chelsea Manning, Caroline Sinders, Cooper Quintin, and Antonia Valencia