LangChain4j
An open-source Java library for building LLM applications on the JVM, with one API over 20+ model providers and 30+ embedding stores, plus tools, agents, MCP and RAG pipelines.
About LangChain4j
Most LLM libraries target Python or JavaScript, leaving Java teams to write their own clients for each model provider and vector store.
Who it’s for
- Java and Kotlin developers adding chat, tools or RAG to existing services
- Teams on Spring Boot, Quarkus, Helidon or Micronaut that want framework integrations
When to consider it
Consider LangChain4j when you want to call LLMs from Java through a unified API, switch providers or vector stores without rewriting code, and use high-level AI Services for tool calling, chat memory and RAG.
Tradeoffs & limitations
- Apache-2.0 licensed and free; requires JDK 17 or newer, and model and vector-store usage is billed by the providers you connect.
- Despite the name it is an independent Java library, not a port of Python LangChain, so APIs and releases do not match LangChain.
SOTA overview · Documentation-based assessment · Sources & review method
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Sources & review method
Documentation-based assessment · Nov 1, 2026 · Prepared with AI assistance; not a hands-on benchmark.
Checked by SOTA · AI-assisted documentation review. Selection advice is our assessment; verify current requirements for your deployment.
Import history & original evidence
LangChain4j official website
An open-source Java library for building LLM applications on the JVM, with one API over 20+ model providers and 30+ embedding stores, plus tools, agents, MCP and RAG pipelines.
Based on official pages and announcements checked on 2026-11-01. No hands-on test, performance benchmark or popularity ranking is claimed.