Agent2Agent Protocol

license

Apache-2.0(OSI)

source

public(spec + reference SDKs in 6 languages)

governance

Linux Foundation (vendor-neutral, Google-contributed)

core-gated

ungated(the Linux Foundation project sells nothing - one Apache-2.0 LICENSE at the root, no ee/ or enterprise/ path, and all six reference SDKs published as public a2aproject repos on public package registries)

Reference spec and SDKs are Apache-2.0 under neutral LF governance; for a protocol this is the openness ceiling. Nothing is gated, established by a direct read of the repo: the finding rests on there being nothing to gate with rather than on a pricing page saying so. The root tree is LICENSE, GOVERNANCE.md, MAINTAINERS.md, specification/, docs/ and adrs/ with no ee/, enterprise/ or commercial/ path, and the README's closing section reads "The A2A Protocol is an open source project under the Linux Foundation, contributed by Google. It is licensed under the Apache License 2.0 and is open to contributions from the community." All six reference SDKs are separate public a2aproject repos installable from public registries - a2a-sdk on PyPI, github.com/a2aproject/a2a-go, @a2a-js/sdk on npm, Maven, NuGet and a2a-lf on crates.io. There is no vendor product beside the protocol, so there is no paid tier, no license key and no closed package.

• https://github.com/a2aproject/A2A recorded 2026-06-04

  Apache-2.0 license, LF-hosted open protocol, spec v1.0.1 + 6-language SDKs, ~24k stars

• https://api.github.com/repos/a2aproject/A2A recorded 2026-08-12

  Repo metadata: license spdx_id Apache-2.0, default branch main, 25,300 stars, not archived.

• https://api.github.com/repos/a2aproject/A2A/contents recorded 2026-08-12

  Root tree. LICENSE, CODE_OF_CONDUCT.md, CONTRIBUTING.md, GOVERNANCE.md, MAINTAINERS.md, SECURITY.md, adrs, docs, scripts, specification. No ee/, enterprise/, commercial/ or proprietary/ path, and no second LICENSE anywhere at the root.

• https://raw.githubusercontent.com/a2aproject/A2A/main/README.md recorded 2026-08-12

  Closing section: "The A2A Protocol is an open source project under the Linux Foundation, contributed by Google. It is licensed under the Apache License 2.0 and is open to contributions from the community." The SDK list links six separate public repos - a2a-python (pip install a2a-sdk), a2a-go, a2a-js (npm), a2a-java (maven), a2a-dotnet (NuGet) and a2a-rs (cargo add a2a-lf). No paid tier, hosted service or enterprise edition is mentioned.

For a protocol, adoption is measured as breadth rather than as a usage count, because no per-user figure is published anywhere. The Linux Foundation reports supporting organizations grown from more than 50 to over 150, including AWS, Cisco, Google, IBM, Microsoft, Salesforce, SAP and ServiceNow, with Azure AI Foundry, Copilot Studio and Amazon Bedrock AgentCore Runtime integrating the protocol, in-production use at Microsoft, AWS, Salesforce, SAP and ServiceNow, embedding into Google Cloud, and five production-ready SDK languages. Breadth across the three major clouds plus enterprise production puts effective downstream reach in the 1-10M band, though this is a count of organizational support rather than a measured per-user figure.

• https://www.linuxfoundation.org/press/a2a-protocol-surpasses-150-organizations-lands-in-major-cloud-platforms-and-sees-enterprise-production-use-in-first-year recorded 2026-08-13

  Dated 2026-04-09. "Since April 2025, the number of supporting organizations has grown from more than 50 to over 150 - including AWS, Cisco, Google, IBM, Microsoft, Salesforce, SAP, and ServiceNow. The core repository has surpassed 22,000 GitHub stars, and the SDK ecosystem has expanded from a single Python implementation to five production-ready languages." Microsoft in Azure AI Foundry and Copilot Studio, AWS through Amazon Bedrock AgentCore Runtime. No user or request count.

• https://github.com/a2aproject/A2A recorded 2026-08-13

  Repo page, 25,336 stargazers, Apache-2.0, spec plus the reference SDK list.

A2A is a wire protocol for agent interoperability, and a protocol is not benchmarked, so capability is deliberately left unscored: openness and adoption-breadth carry the whole signal. The repository publishes a specification, architecture decision records, governance documents and reference SDKs, and no benchmark, leaderboard or measured performance number for the protocol appears there or anywhere the project points - what was looked for and not found is a published score of any kind ranking A2A against a peer. The blank is a policy rather than a gap waiting to be filled, and no score is invented to close it. The reason is that neither capability question one might ask of a protocol survives scrutiny. Breadth of implementation is adoption wearing a capability label, and this record's adoption is already banded on exactly that - more than 150 supporting organizations by the Linux Foundation's count - so scoring breadth here would let one instrument vote twice. Spec maturity is genuinely independent of uptake, but no rubric on this map has a ladder for it, and with only two protocols on the map there is nothing to anchor a comparison against. One cost comes with the blank and is stated rather than papered over: with no capability score the maturity calculation falls through to adoption alone, so this record computes its maturity from a single axis. The Model Context Protocol has the same shape and carries the same policy.

• https://github.com/a2aproject/A2A recorded 2026-08-13

  Repo page - specification, ADRs, governance and reference SDK links. Described as an open protocol and spec, not a runtime. No benchmark result, leaderboard entry or performance figure published.

• https://github.com/a2aproject/A2A recorded 2026-08-14

  A specification repository - spec, ADRs, governance, maintainers and the reference SDK links - with no benchmark, leaderboard or performance figure anywhere on it.