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MCP Java SDK

open source / Overall score: 2.0

The official Java SDK for the Model Context Protocol, maintained in collaboration with Spring AI. Synchronous and asynchronous client and server over stdio, Server-Sent Events and Streamable HTTP, validated against the MCP conformance suite.

Maven Central publishes no download counts and the legacy Solr index returns nothing for this group, so adoption is read from stars. Unlike its siblings this repository carries a plain MIT licence rather than the project's dual transition file.

Openness

5 high confidence

5.0

license: MIT(OSI)
source: public(the core SDK and its Spring integrations)
self-host: yes(a library you build against)
core features withheld: no — nothing withheld from the published tree

Plain MIT, and the only member of the official SDK family whose licence classifies cleanly - the others carry the project's dual transition file that GitHub reports as NOASSERTION.

https://api.github.com/repos/modelcontextprotocol/java-sdk recorded 2026-09-17
Repository metadata: spdx_id MIT, 3,698 stars, not archived, not a fork, last pushed 2026-09-17, description "The official Java SDK for Model Context Protocol servers and clients. Maintained in collaboration with Spring AI".
https://raw.githubusercontent.com/modelcontextprotocol/java-sdk/main/LICENSE recorded 2026-09-17
The LICENSE body: the verbatim MIT text under "Copyright (c) 2025 the original author or authors."

Adoption

2 low confidence

2.0

Maven Central publishes no download figures for Java packages, so there is no usage-volume channel available, and GitHub stars are the only signal left.

https://api.github.com/repos/modelcontextprotocol/java-sdk recorded 2026-09-17
Repository metadata for modelcontextprotocol/java-sdk: 3,698 stargazers.

Capability

not assessed

No score is given because the primitive set cannot be confirmed: the README covers both roles and three transports but links the primitive list to a features page that 404s, and the project's GitHub Pages site serves only a stub. The SDK passes 40 of 40 server conformance scenarios against the 2025-11-25 suite, which is a different claim from enumerating which primitives are implemented.

https://raw.githubusercontent.com/modelcontextprotocol/java-sdk/main/README.md recorded 2026-09-17
The README: "MCP supports both clients ... and servers ... The SDK provides support for both sides", with "STDIO transports for inter-process communication using pipes" and "Streaming transports such as Server-Sent Events and Streamable HTTP". It names no target specification version outside a conformance command line (--spec-version 2025-11-25) and does not enumerate tools, resources or prompts, linking to a separate features page instead. Conformance: Server "40/40 passed (100%)", Client "3/4 scenarios, 9/10 checks passed".

Verified 2026-09-17