head to head · open source
Vector vs client_java
Vector has 22,589 GitHub stars, 2,286 forks, 2,512 open issues and last shipped 2 days ago. client_java has 2,289 stars, 833 forks, 23 open issues and last shipped today. Vector leads on adoption by 887% (22,589 vs 2,289 stars). Vector is written in Rust under MPL-2.0; client_java is written in Java under Apache-2.0. Vector has attracted 10% as many forks as stars, client_java 36%. client_java was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (metrics), 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
| Vector | client_java | |
|---|---|---|
| GitHub stars | ★ 23K | ★ 2.3K |
| License | MPL-2.0 | Apache-2.0 |
| Written in | Rust | Java |
| Last push | 2026-09-18 | 2026-09-20 |
| Forks | ⑂ 2.3K | ⑂ 833 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Vector if
- You weight community size — 23K stars and counting
- You want the MPL-2.0 license terms
- Your stack matches Rust
- 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 Vector
Vector is an open source observability data pipeline written in Rust and licensed under MPL 2.0. It operates as an end to end system for collecting, transforming, and routing logs and metrics within the cloud native monitoring ecosystem. The project is maintained by Datadog's Community Open Source Engineering team, and its topics include agent, cloud native, data transformation, datadog, etl, events, forwarder, logs, metrics, and monitoring.
read the full Vector overview →
About client_java
Prometheus instrumentation library for JVM applications — it lets Java services expose metrics that Prometheus scrapes, and it is aimed at Java and JVM developers and the platform, SRE, and observability teams that run Prometheus alongside them.
read the full client_java overview →
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Frequently asked questions
Is Vector or client_java more popular?
Vector has 22,589 GitHub stars and client_java has 2,289. Vector has the larger community by that measure.
Are Vector and client_java free?
Both are open source. Vector is licensed under MPL-2.0 and client_java under Apache-2.0. Neither carries a licence fee.
What is the difference between Vector and client_java?
Vector is written in Rust 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, Vector or client_java?
Choose Vector if you want the larger community (22,589 stars) or its MPL-2.0 licence terms. Choose client_java if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.