head to head · open source
zipkin vs pup
zipkin has 17,464 GitHub stars, 3,098 forks, 175 open issues and last shipped 2 months ago. pup has 1,014 stars, 121 forks, 12 open issues and last shipped 2 days ago. zipkin leads on adoption by 1,622% (17,464 vs 1,014 stars). zipkin is written in Java under Apache-2.0; pup is written in Rust under Apache-2.0. zipkin has attracted 18% as many forks as stars, pup 12%. pup 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 | pup | |
|---|---|---|
| GitHub stars | ★ 17K | ★ 1.0K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Java | Rust |
| Last push | 2026-08-06 | 2026-09-18 |
| Forks | ⑂ 3.1K | ⑂ 121 |
| 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 pup if
- You want the pup feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Rust
- You evaluated both and pup 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 pup
Pup is an Apache 2.0 licensed, Rust written command line client from Datadog that exposes more than 200 commands across over 33 Datadog product domains, letting AI agents and the humans who supervise them query observability data from a terminal.
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Frequently asked questions
Is zipkin or pup more popular?
zipkin has 17,464 GitHub stars and pup has 1,014. zipkin has the larger community by that measure.
Are zipkin and pup free?
Both are open source. zipkin is licensed under Apache-2.0 and pup under Apache-2.0. Neither carries a licence fee.
What is the difference between zipkin and pup?
zipkin is written in Java and pup in Rust. 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 pup?
Choose zipkin if you want the larger community (17,464 stars) or its Apache-2.0 licence terms. Choose pup if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.