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LangChain4j

Java library with one API over LLM providers and vector stores, plus tools, RAG and integrations for Quarkus and Spring Boot.

Harness by LangChain4j

IndexedApache-2.0★ 13,288
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About

LangChain4j is an open-source Java library that gives one API across 20+ LLM providers and 30+ embedding stores, so models and vector stores can be swapped without rewriting code. It provides prompt templating, chat memory, function calling, agents and RAG. It is built for Java rather than ported from Python LangChain, and integrates with Quarkus, Spring Boot, Helidon and Micronaut.

Use cases: agent-orchestration, knowledge-base

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Fact sheet

Languages
JavaREADME
Packages
dev.langchain4j:langchain4j (maven)README
Memory
short-term, vectorREADME
Model providers
openai, googleREADME
Maturity
Stablegithub.com

Facts extracted by Claude Haiku 5.5 from the linked sources on Oct 24, 2026; reviewed Oct 24, 2026. Wrong fact? Tell us.

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    Stars
    13,288
    Forks
    2,636
    Open issues
    658
    Last commit
    Oct 23, 2026 (4 days ago)
    Last release
    Oct 8, 2026 (19 days ago)

    From GitHub (fetched Oct 24, 2026).

    Details

    Packages
    maven dev.langchain4j:langchain4j
    License
    Apache-2.0
    Repository
    github.com/langchain4j/langchain4j
    Website
    docs.langchain4j.dev/
    Docs
    docs.langchain4j.dev/
    First seen
    Oct 24, 2026
    Last checked
    Oct 24, 2026
    Source
    READMEWebsiteDocsgithub-graphql
    Cite this page

    LangChain4j. Agent Mart. https://agentmart.dev/harnesses/langchain4j (last updated 2026-10-24)