head to head · open source
Tongsuo vs certspotter
Tongsuo has 1,535 GitHub stars, 260 forks, 160 open issues and last shipped 13 days ago. certspotter has 1,174 stars, 104 forks, 18 open issues and last shipped 7 days ago. Tongsuo leads on adoption by 31% (1,535 vs 1,174 stars). Tongsuo is written in C under Apache-2.0; certspotter is written in Go under MPL-2.0. Tongsuo has attracted 17% as many forks as stars, certspotter 9%. certspotter was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (pki, security), so they are genuine substitutes rather than adjacent tools.
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
| Tongsuo | certspotter | |
|---|---|---|
| GitHub stars | ★ 1.5K | ★ 1.2K |
| License | Apache-2.0 | MPL-2.0 |
| Written in | C | Go |
| Last push | 2026-09-07 | 2026-09-13 |
| Forks | ⑂ 260 | ⑂ 104 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Tongsuo if
- You weight community size — 1.5K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches C
- You value the larger contributor base for long-term maintenance
pick certspotter if
- You want the certspotter feature set and don't need the biggest community
- You prefer the MPL-2.0 license terms
- Your stack matches Go
- You evaluated both and certspotter fits your workflow better
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 →
About certspotter
Cert Spotter is a lightweight, open source Certificate Transparency log monitor from SSLMate that watches Certificate Transparency logs and alerts you when an SSL/TLS certificate is issued for any domain on your watch list, aimed at site operators, security teams, and PKI administrators who need to catch unauthorized certificates without operating a database.
read the full certspotter overview →
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Frequently asked questions
Is Tongsuo or certspotter more popular?
Tongsuo has 1,535 GitHub stars and certspotter has 1,174. Tongsuo has the larger community by that measure.
Are Tongsuo and certspotter free?
Both are open source. Tongsuo is licensed under Apache-2.0 and certspotter under MPL-2.0. Neither carries a licence fee.
What is the difference between Tongsuo and certspotter?
Tongsuo is written in C and certspotter in Go. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Tongsuo or certspotter?
Choose Tongsuo if you want the larger community (1,535 stars) or its Apache-2.0 licence terms. Choose certspotter if its feature set, stack or MPL-2.0 licence fits better. Both are self-hostable.