head to head · open source
zipkin vs openwolf
zipkin has 17,464 GitHub stars, 3,098 forks, 175 open issues and last shipped 2 months ago. openwolf has 2,351 stars, 212 forks, 56 open issues and last shipped 5 days ago. zipkin leads on adoption by 643% (17,464 vs 2,351 stars). zipkin is written in Java under Apache-2.0; openwolf is written in TypeScript under AGPL-3.0. zipkin has attracted 18% as many forks as stars, openwolf 9%. openwolf was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (observability), 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
| zipkin | openwolf | |
|---|---|---|
| GitHub stars | ★ 17K | ★ 2.4K |
| License | Apache-2.0 | AGPL-3.0 |
| Written in | Java | TypeScript |
| Last push | 2026-08-06 | 2026-09-15 |
| Forks | ⑂ 3.1K | ⑂ 212 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick zipkin if
- You weight community size — 17K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Java
- You value the larger contributor base for long-term maintenance
pick openwolf if
- You want the openwolf feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches TypeScript
- You evaluated both and openwolf fits your workflow better
About zipkin
Zipkin is a distributed tracing system maintained under the OpenZipkin organization and written in Java, released under the Apache 2.0 license. It lives in the Java and JVM ecosystem as a standalone server, while its instrumentation libraries span many languages. The project gathers the timing data needed to troubleshoot latency problems in service architectures, and it covers both the collection and the lookup of that data.
read the full zipkin overview →
About openwolf
OpenWolf is an open source TypeScript tool that keeps portable project memory for coding agents such as Claude Code, Codex and OpenCode and measures token usage from harness transcripts, aimed at developers who lose context between sessions or across agents.
read the full openwolf overview →
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Frequently asked questions
Is zipkin or openwolf more popular?
zipkin has 17,464 GitHub stars and openwolf has 2,351. zipkin has the larger community by that measure.
Are zipkin and openwolf free?
Both are open source. zipkin is licensed under Apache-2.0 and openwolf under AGPL-3.0. Neither carries a licence fee.
What is the difference between zipkin and openwolf?
zipkin is written in Java and openwolf in TypeScript. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, zipkin or openwolf?
Choose zipkin if you want the larger community (17,464 stars) or its Apache-2.0 licence terms. Choose openwolf if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.