head to head · open source
Signal vs Tongsuo
Signal has 29,359 GitHub stars, 6,890 forks, 498 open issues and last shipped yesterday. Tongsuo has 1,535 stars, 260 forks, 160 open issues and last shipped 12 days ago. Signal leads on adoption by 1,813% (29,359 vs 1,535 stars). Signal is written in Kotlin under AGPL-3.0; Tongsuo is written in C under Apache-2.0. Signal has attracted 23% as many forks as stars, Tongsuo 17%. Signal was the more recently maintained of the two, and both are self-hostable with no licence fee.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Signal | Tongsuo | |
|---|---|---|
| GitHub stars | ★ 29K | ★ 1.5K |
| License | AGPL-3.0 | Apache-2.0 |
| Written in | Kotlin | C |
| Last push | 2026-09-18 | 2026-09-07 |
| Forks | ⑂ 6.9K | ⑂ 260 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Signal if
- You weight community size — 29K stars and counting
- You want the AGPL-3.0 license terms
- Your stack matches Kotlin
- You value the larger contributor base for long-term maintenance
pick Tongsuo if
- You want the Tongsuo feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches C
- You evaluated both and Tongsuo fits your workflow better
About Signal
Signal Android is a secure messaging application for Android devices that delivers private communication via end to end encryption. Developed by Signal Messenger, LLC, it operates within the broader Signal ecosystem, which includes official iOS and desktop clients. The app uses mobile data or Wi Fi to send and receive encrypted messages, voice calls, and video calls without relying on traditional SMS or telephony infrastructure.
read the full Signal overview →
About Tongsuo
Tongsuo (铜锁) is an open source C library of modern cryptographic primitives and secure communication protocols, developed under the OpenAtom Foundation, and it is built for teams that need Chinese commercial cryptography, TLS, PKI, and privacy preserving primitives from a single dependency.
read the full Tongsuo overview →
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Frequently asked questions
Is Signal or Tongsuo more popular?
Signal has 29,359 GitHub stars and Tongsuo has 1,535. Signal has the larger community by that measure.
Are Signal and Tongsuo free?
Both are open source. Signal is licensed under AGPL-3.0 and Tongsuo under Apache-2.0. Neither carries a licence fee.
What is the difference between Signal and Tongsuo?
Signal is written in Kotlin and Tongsuo in C. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Signal or Tongsuo?
Choose Signal if you want the larger community (29,359 stars) or its AGPL-3.0 licence terms. Choose Tongsuo if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.