head to head · open source
Zen vs certspotter
Zen has 4,225 GitHub stars, 143 forks, 14 open issues and last shipped 2 days ago. certspotter has 1,174 stars, 104 forks, 18 open issues and last shipped 7 days ago. Zen leads on adoption by 260% (4,225 vs 1,174 stars). Zen is written in Go under MIT; certspotter is written in Go under MPL-2.0. Zen has attracted 3% as many forks as stars, certspotter 9%. Zen 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
| Zen | certspotter | |
|---|---|---|
| GitHub stars | ★ 4.2K | ★ 1.2K |
| License | MIT | MPL-2.0 |
| Written in | Go | Go |
| Last push | 2026-09-18 | 2026-09-13 |
| Forks | ⑂ 143 | ⑂ 104 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Zen if
- You weight community size — 4.2K stars and counting
- You want the MIT license terms
- Your stack matches Go
- 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 Zen
Zen is an open source desktop application written in Go for Windows, macOS, and Linux under the MIT license. It operates as a system wide ad blocker and privacy guard, so it applies to traffic from applications on the machine rather than only to browser tabs. It lives in the desktop security and privacy ecosystem, where users want filtering without browser extensions.
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 Zen or certspotter more popular?
Zen has 4,225 GitHub stars and certspotter has 1,174. Zen has the larger community by that measure.
Are Zen and certspotter free?
Both are open source. Zen is licensed under MIT and certspotter under MPL-2.0. Neither carries a licence fee.
What is the difference between Zen and certspotter?
Zen is written in Go 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, Zen or certspotter?
Choose Zen if you want the larger community (4,225 stars) or its MIT licence terms. Choose certspotter if its feature set, stack or MPL-2.0 licence fits better. Both are self-hostable.