A Java library that helps run agentic applications as A2A servers following the Agent2Agent (A2A) Protocol.
A multi-module Maven library providing client and server support for A2A agent communication over JSON-RPC, gRPC, and REST transports.
Full documentation is available at a2aproject.github.io/a2a-java.
- Server Guide — Run your agentic Java application as an A2A server
- Client Guide — Communicate with any A2A-compliant agent
- Community Articles — Tutorials, blog posts, and videos
- Announcements — Release announcements and project news
- Contributing — Developer guide for contributing
Requires Java 17+.
Add the A2A Java SDK reference server for JSON-RPC to your Maven project:
<dependency>
<groupId>org.a2aproject.sdk</groupId>
<artifactId>a2a-java-sdk-reference-jsonrpc</artifactId>
<!-- Use a released version from https://github.com/a2aproject/a2a-java/releases -->
<version>${org.a2aproject.sdk.version}</version>
</dependency>See the Server Guide for full setup instructions.
mvn clean installWe copy https://github.com/a2aproject/A2A/blob/main/specification/grpc/a2a.proto to the spec-grpc/ project, and adjust the java_package option to be as follows:
option java_package = "org.a2aproject.sdk.grpc";
Then build the spec-grpc module with mvn clean install -Dskip.protobuf.generate=false to regenerate the gRPC classes in the org.a2aproject.sdk.grpc package.
- Hello World Server — Java A2A server with a Python client
- Hello World Client — Java A2A client with a Python server
- a2a-samples — More agent examples
Community contributed integrations with various Java runtimes:
- Quarkus — This project contains the reference implementations for JSON-RPC, gRPC, and HTTP+JSON (REST) transports.
- Jakarta EE — a2a-jakarta works with any runtime supporting the Jakarta EE Web Profile.
To contribute an integration, see CONTRIBUTING_INTEGRATIONS.md.
See the extras folder for optional add-ons (OpenTelemetry, JPA-backed task store, Kafka-based replicated queue manager, Vert.x and Android HTTP clients).
This project is licensed under the terms of the Apache 2.0 License.
See CONTRIBUTING.md for contribution guidelines.