# Building a Quarkus LangChain4j Extension for Java LLM Applications

DevFeed: [Building a Quarkus LangChain4j Extension for Java LLM Applications](<https://devfeed.tech/articles/quarkus-langchain4j-extension-from-grounds-up-23027.md>)

Original publisher: [Read original article](<https://www.javaadvent.com/2025/12/quarkus-langchain4j-extension-from-grounds-up.html>)

Author: Martin Toshev

Published: 2025-12-02T04:33:13Z

Content type: tutorial

Language: en

Sources: [Java Advent Calendar](<https://devfeed.tech/sources/java-advent-calendar.md>)

Topics: [Quarkus](<https://devfeed.tech/topics/quarkus.md>), [Java](<https://devfeed.tech/topics/java.md>), [Large Language Model](<https://devfeed.tech/topics/llm.md>), [Framework](<https://devfeed.tech/topics/framework.md>), [observability](<https://devfeed.tech/topics/observability.md>), [tracing](<https://devfeed.tech/topics/tracing.md>)

Tags: [2025](<https://devfeed.tech/tags/2025.md>), [agentic](<https://devfeed.tech/tags/agentic.md>), [ai](<https://devfeed.tech/tags/ai.md>), [frameworks](<https://devfeed.tech/tags/frameworks.md>), [healthcare](<https://devfeed.tech/tags/healthcare.md>), [java](<https://devfeed.tech/tags/java.md>), [langchain4j](<https://devfeed.tech/tags/langchain4j.md>), [large-language-models](<https://devfeed.tech/tags/large-language-models.md>), [observability](<https://devfeed.tech/tags/observability.md>), [opentelemetry](<https://devfeed.tech/tags/opentelemetry.md>), [quarkus](<https://devfeed.tech/tags/quarkus.md>), [tracing](<https://devfeed.tech/tags/tracing.md>)

## AI overview

This tutorial explains how the Quarkus LangChain4j extension simplifies integrating Java applications with large language models. It covers build-time and native-image optimizations, CDI-based AI service discovery, type-safe configuration, Quarkus dev mode integration, and observability features before demonstrating an agentic healthcare application.

## Source excerpt

LangChain4j is a top (if not the top) library in use for integrating Java applications with various LLMs (large language models). It provides a number of features such as a unified API for LLM integration, support for vector stores, prompt templates, RAG (retrievalaugmented generation) and more. While we can use it directly in popular frameworks [...] The post Quarkus LangChain4j extension from grounds up appeared first on JVM Advent.