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HomeLearnRunning an A2A server on Cloudflare Workers

Updated 2026-10-23 · applies to a2a-exposed 0.8.15

Running an A2A server on Cloudflare Workers

You can write an A2A server, or you can deploy this Worker and leave your agent where it already runs.

Three ways

  1. Build an agent on Workers. Cloudflare's agents examples and @a2a-js/sdk show an A2A server next to a Durable Object. The agent and the endpoint are the same program. Follow those projects for that design. This site covers the agent address in front of an existing agent.
  2. Adapt an existing server. Edge adapters (Hono and others in the A2A JavaScript ecosystem) wrap a server you already wrote. You still operate that server.
  3. Deploy a2a-exposed and leave the agent where it is. The Worker serves the card, the JSON-RPC endpoint, pairing and the task store. Your agent is a webhook or a poll. Self-host is one command on the quick start. The free plan and a workers.dev hostname are enough to start. See workers.dev.

These are complementary. An agent that already lives somewhere else gets a public card from this Worker.

What the Worker has to serve

An A2A endpoint needs a card, a JSON-RPC method handler, a way to authenticate peers, and a place to store tasks. A self-hosted init stores tasks in D1. A hosted deploy uses one SQLite Durable Object per tenant. Version selection is the A2A-Version header or the method name. OAuth device-flow endpoints live on the same host. The method list is protocol support.

Free plan

init without --hostname targets workers.dev. PBKDF2 for the approval password defaults to 100,000 iterations. Error 1102 means you hit the free-plan CPU limit; lower it with --pbkdf2-iterations 50000 (minimum 50,000). Error 1042 right after deploy is propagation, not a bad card.

Hosted

A hosted address at <name>.a2a.exposed is in open beta. It is the same open-source Worker, on our Cloudflare account, with data at rest in the EU. Start free, or deploy the Worker in your account.