📢 Documentation Update
This README has been updated to reflect our new Docusaurus-based documentation site. For the most current documentation, please visit the official Apache Juneau website.
Apache Juneau
Apache Juneau™ is a single cohesive Java ecosystem consisting of a comprehensive toolkit for marshalling POJOs to a wide variety of content types using a common framework, along with universal REST server and client APIs for creating Swagger-based self-documenting REST interfaces.
⚠️ Upgrading from 9.x? The project is currently developing the 10.0.0 release, which includes a number of breaking changes (the public ObjectRest class removed, SerializerSet/ParserSet lookups now returning Optional, the next-gen RestClient no longer implicitly defaulting to JSON, the juneau-assertions/juneau-bct/juneau-junit5 modules merged into a single juneau-bct artifact, and the legacy juneau-my-jetty-microservice/juneau-examples-rest modules removed, among others). See the 10.0.0 Migration Guide for the full list before upgrading.
Key Features
- Universal Serialization - Marshal POJOs to JSON, XML, HTML, URL-Encoding, UON, MessagePack, CSV, and more
- REST Services - Create self-documenting REST interfaces with automatic Swagger/OpenAPI generation
- Microservices - Build lightweight, standalone microservices with embedded Jetty
- Configuration Management - Sophisticated configuration file API with variable resolution
- Fluent Assertions - Powerful testing framework with fluent-style assertions
- Type Conversion - Lightweight, MarshallingContext-free converter framework with caching and broad type support
- Large-Dataset Streaming - BeanSupplier/BeanConsumer/BeanChannel APIs for serializing and parsing large datasets without loading all elements into memory; supports direct database integration via lifecycle methods (begin/acceptThrows/onError/complete)
- MCP (Model Context Protocol) Support - First-party server and client support for exposing REST resources as MCP tools/prompts/resources, or consuming MCP servers from Java, for both the
2025-06-18 and 2026-07-28 protocol revisions
- Zero Dependencies - Core marshalling requires no external dependencies
MCP (Model Context Protocol) Support
Apache Juneau ships first-party MCP integration, built the same way as the rest of the framework: annotation-driven, POJO-based, no magic. The module family is split into revision-neutral cores plus thin adapters per protocol revision, so a 2025-06-18-only deployment never pulls in 2026-07-28-only dependencies (OAuth 2.1, JWT, reactive-streams SSE, etc.):
- juneau-bean-jsonrpc - revision-neutral JSON-RPC 2.0 envelope beans, with
juneau-bean-mcp-v20250618 / juneau-bean-mcp-v20260728 adapters for each revision's wire beans.
- juneau-rest-server-mcp - revision-neutral server dispatch core, with
juneau-rest-server-mcp-v20250618 / juneau-rest-server-mcp-v20260728 adapters for exposing tools, prompts, and resources (dedicated servlet or drop-in mixin, plain or Spring Boot).
- juneau-rest-client-mcp - revision-neutral client core, with
juneau-rest-client-mcp-v20250618 / juneau-rest-client-mcp-v20260728 typed client facades, plus juneau-rest-client-mcp-auth for the client-side OAuth 2.1 acquisition flow.
- juneau-examples-mcp - a runnable first-party example (notes-service demo, with plain, Spring Boot, and OAuth-secured variants).
The 2026-07-28 revision is a strict superset of 2025-06-18 and is where new capability work (Multi-Round-Trip Requests/elicitation, subscriptions, cache hints, trace-context propagation) lands going forward. See MCP (Model Context Protocol) for the quickstart, setup guide, and full API reference.
Documentation & Resources
Official Resources
This is the beginning of the README. Read the rest at the original. Read the full README ↗
