Need a secure chat app built?
I build messaging that only the people in the conversation can read — on the Signal Protocol — and group voice and video calling on WebRTC, for teams that can’t afford a leak.
How the secure messaging I build works, in 36 seconds — messages only the people in the conversation can read, a server that relays ciphertext and never holds the keys, a fresh key for every message, safety numbers to rule out anyone in the middle, and group calls.
Calls that stay in the room, in 43 seconds — encrypted one-to-one and group calls on WebRTC with media over DTLS-SRTP, the active speaker in focus, video that steps down when bandwidth drops while audio keeps going, screen sharing with in-call messages on the Signal Protocol, and audio-only in the background.
End-to-end encryption on the Signal Protocol — X3DH key agreement, the Double Ratchet and Sealed Sender.
Multi-device delivery, @mentions, message editing, delete for everyone and search, without giving up encryption.
An MFA-protected encrypted file vault, and encrypted on-device storage with SQLCipher.
Group voice and video calls on WebRTC and mediasoup — scaled from 6 to 10 participants, with video paused for off-screen participants.
Calls that ring even when the app is closed, through CallKit on iOS and Telecom on Android.
A permanent regression test for every fixed bug — about 1,430 tests took the messenger from 51% to 74% coverage.
What does end-to-end encryption mean for my app?
Messages are encrypted on the sender’s device and decrypted only on the recipients’ devices, so your servers — and anyone who breaches them — see only ciphertext. The Signal Protocol also keeps changing keys as the conversation goes, so one leaked key doesn’t expose the rest of the conversation.
Can you build an app like WhatsApp?
Yes — its core is what I built for Bravo Secure: chat encrypted end to end on the Signal Protocol with multi-device delivery, plus group voice and video calls that ring even when the phone’s app is closed.
Can you add encrypted chat or video calling to an existing app?
Yes. Messaging and calling can be built as modules inside an existing React Native app and backend, or as a standalone app.
How many people can join a group call?
The calls I shipped for Bravo Secure support 10 participants, scaled up from 6. They run on mediasoup, a selective forwarding unit, so each person uploads one stream instead of one per participant.
Should I use a chat SDK or build a custom encrypted messenger?
A hosted chat SDK gets a basic chat running fastest. A custom build on the Signal Protocol makes sense when you need to hold your own keys and data, decide where messages are stored, or avoid per-user fees as you grow.
Does end-to-end encryption add work to an app?
Some. Key management, multi-device delivery, search and message editing all have to work without the server being able to read messages. Designing for that from day one costs far less than adding it later.
Do you work with clients outside Bangladesh?
Yes. I work remotely with clients in the UAE, South Africa and the UK from Dhaka (GMT+6) — in English, with regular demos.
How do we start?
Email hello@ranak.bio or message me on WhatsApp with a few lines about the project. I usually reply within a day.