head to head · open source
Apache SkyWalking vs client_java
Apache SkyWalking has 24,988 GitHub stars, 6,632 forks, 41 open issues and last shipped 2 days ago. client_java has 2,291 stars, 837 forks, 23 open issues and last shipped yesterday. Apache SkyWalking leads on adoption by 991% (24,988 vs 2,291 stars). Apache SkyWalking is written in Java under Apache-2.0; client_java is written in Java under Apache-2.0. Apache SkyWalking has attracted 27% as many forks as stars, client_java 37%. client_java was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (metrics, prometheus), 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
| Apache SkyWalking | client_java | |
|---|---|---|
| GitHub stars | ★ 25K | ★ 2.3K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Java | Java |
| Last push | 2026-11-03 | 2026-11-04 |
| Forks | ⑂ 6.6K | ⑂ 837 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Apache SkyWalking if
- You weight community size — 25K 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 client_java if
- You want the client_java feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Java
- You evaluated both and client_java fits your workflow better
About Apache SkyWalking
Apache SkyWalking ========== SkyWalking : an APM (Application Performance Monitoring) system, especially designed for microservices, cloud native and container based architectures. Abstract SkyWalking is an open source APM system that provides monitoring, tracing and diagnosing capabilities for distributed systems in Cloud Native architectures. Distributed Tracing End to end distributed tracing. Service topology analysis, service centric observability and APIs dashboards. Agents for your stack Java, .Net Core, PHP, NodeJS, Golang, LUA, Rust, C++, Client JavaScript and Python agents with active development and…
read the full Apache SkyWalking overview →
About client_java
Prometheus Java Metrics Library [![Build][build badge]][build workflow] [build badge]: [build workflow]: Documentation Contributing and community See CONTRIBUTING.md and the community section of the Prometheus homepage. The Prometheus Java community is present on the CNCF Slack on prometheus java , and we have a fortnightly community call in the Prometheus public calendar. Previous Releases The source code for 0.16.0 and older is on the simpleclient branch. License Apache License 2.0, see LICENSE.
read the full client_java overview →
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Frequently asked questions
Is Apache SkyWalking or client_java more popular?
Apache SkyWalking has 24,988 GitHub stars and client_java has 2,291. Apache SkyWalking has the larger community by that measure.
Are Apache SkyWalking and client_java free?
Both are open source. Apache SkyWalking is licensed under Apache-2.0 and client_java under Apache-2.0. Neither carries a licence fee.
What is the difference between Apache SkyWalking and client_java?
Apache SkyWalking is written in Java and client_java in Java. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Apache SkyWalking or client_java?
Choose Apache SkyWalking if you want the larger community (24,988 stars) or its Apache-2.0 licence terms. Choose client_java if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.