langchain4j/langchain4j

Vector Databases

LangChain4j is an open-source Java library that simplifies the integration of LLMs into Java applications through a unified API, providing access to popular LLMs and vector databases. It makes implementing RAG, tool calling (including support for MCP), and agents easy. LangChain4j integrates seamlessly with various enterprise Java frameworks.

GitHub →Website →

8.4

GitHub Metrics

Stars

13.0k

Forks

2.5k

Open Issues

864

Watchers

117

Contributors

475

Weekly Commits

Language

Java

License

Apache-2.0

Last Commit

Aug 27, 2026

Created

Jun 20, 2023

Latest Release

1.19.0

Release Date

Aug 14, 2026

Synced: Aug 28, 2026

Quality Scores

Documentation Qualityw: 20%

8.7

Has docs site (https://docs.langchain4j.dev). Description: 344 chars. Stars signal: 12,968. Contributors: 475. Score: 8.7/10

Community Healthw: 20%

8.2

Stars: 12,968. Contributors: 475. Watchers: 117. Forks: 2,504. Issue ratio: 6.6%. Score: 8.2/10

Maintenance Velocityw: 15%

9.8

Last commit: 0d ago. Weekly commits: 34. Latest release: 1.19.0. Maturity bonus: 3.2y old. Score: 9.8/10

API Design & DXw: 20%

7.4

Stars/issues ratio: 15. Typed language: Java. Has documentation site. Permissive license: Apache-2.0. Popularity signal: 12,968 stars. Score: 7.4/10

Production Readinessw: 15%

8.3

Battle-tested: 12,968 stars. Peer review: 475 contributors. Versioned: 1.19.0. Licensed: Apache-2.0. Age: 3.2 years. Maintenance: last commit 0d ago. Score: 8.3/10

Ecosystem Integrationw: 10%

8.6

Fork interest: 2,504. Major ecosystem: Java. Integration-friendly: Apache-2.0. Adoption: 12,968 stars. Has web presence. Score: 8.6/10