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Scaling End-to-End Encrypted Groups at Tula

Encrypting a message is only one part of the system. At scale, we also have to handle membership changes, key distribution, offline users, message fan-out, recovery after failures, database growth,

How We Built Decrypted Push Previews Without Putting Message Content in Push

A generic-first Android notification architecture that keeps push payloads minimal and performs authenticated, device-specific decryption locally.

Exactly Once Decryption in an At-Least-Once Messaging World

How Tula designed a crash-safe receive path where duplicate delivery is normal, but cryptographic state advancement happens at most once.

From seven seconds to 226 milliseconds: document previews under end-to-end encryption

How Tula opens Word documents, slide decks and spreadsheets entirely on your phone — because our servers can't read them, and never will.

We load-tested our Go backend to 2,000 concurrent WebSockets. The app wasn't what broke

Our backend is deliberately boring: a single Go monolith on a 4-core VPS in Nairobi, PostgreSQL on the same box, nginx in front.