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

12.6k

Forks

2.4k

Open Issues

805

Watchers

114

Contributors

444

Weekly Commits

Language

Java

License

Apache-2.0

Last Commit

Jul 17, 2026

Created

Jun 20, 2023

Latest Release

1.18.0

Release Date

Jul 17, 2026

Synced: Jul 18, 2026

Quality Scores

Documentation Qualityw: 20%

8.7

Has docs site (https://docs.langchain4j.dev). Description: 344 chars. Stars signal: 12,635. Contributors: 444. Score: 8.7/10

Community Healthw: 20%

8.1

Stars: 12,635. Contributors: 444. Watchers: 114. Forks: 2,380. Issue ratio: 6.4%. Score: 8.1/10

Maintenance Velocityw: 15%

9.8

Last commit: 1d ago. Weekly commits: 27. Latest release: 1.18.0. Maturity bonus: 3.1y old. Score: 9.8/10

API Design & DXw: 20%

7.4

Stars/issues ratio: 16. Typed language: Java. Has documentation site. Permissive license: Apache-2.0. Popularity signal: 12,635 stars. Score: 7.4/10

Production Readinessw: 15%

8.3

Battle-tested: 12,635 stars. Peer review: 444 contributors. Versioned: 1.18.0. Licensed: Apache-2.0. Age: 3.1 years. Maintenance: last commit 1d ago. Score: 8.3/10

Ecosystem Integrationw: 10%

8.6

Fork interest: 2,380. Major ecosystem: Java. Integration-friendly: Apache-2.0. Adoption: 12,635 stars. Has web presence. Score: 8.6/10