Agent discovery
One page of entry points. Each URL below resolves without an account, an API key or a conversation, and each one is the machine-readable source of truth for what it describes — so nothing here has to be taken on trust.
If you read nothing else, read the manifest. It answers what is this, what does it cost and how do I pay in a single request.
curl -s https://harpd.com/.well-known/harpd-agent.json curl -s https://api.harpd.com/api/agent/v1/pricing curl -s "https://api.harpd.com/api/agent/v1/search?q=video+generator"
Those three calls cost nothing and need no credential. They are enough to decide whether the paid products are worth buying.
What Harpd is, what it can do, which interfaces exist, how payment works and what the response envelope looks like — in one JSON document.
Needs: None
Every product with its price, unit, currency, network and payment protocol. The same numbers that appear in the HTTP 402 challenge, so a price an agent reads is the price it will be charged.
Needs: None
Endpoints, parameters, request and response schemas, error codes, pricing metadata and payment metadata. Generated from the same product catalogue the Worker charges from.
Needs: None
The same products as Model Context Protocol tools, for an agent that speaks MCP rather than raw HTTP. Stateless core (protocol revision 2026-07-28): no session, no handshake, no Mcp-Session-Id.
Needs: None
The underlying data behind the paid answers, published openly under CC BY 4.0. An agent can verify a paid result against the free source instead of trusting it.
Needs: None for the files; payment for the query endpoint
USDC on Base over x402. Harpd never holds funds or keys, and no account, API key or human checkout exists anywhere in the flow.
Needs: A funded agent wallet on Base (or Base Sepolia for testing)
The full journey — discover, free call, paid call, 402, sign, retry, result, citation — written out for each integration style.
Needs: None to read; a wallet to run the paid step
Free permanently, not as a trial. An agent that cannot evaluate the data before paying for it has no way to decide, so discovery, search and the public board never require payment.
| Endpoint | Purpose |
|---|---|
GET /api/agent/v1/manifest | capability + payment manifest |
GET /api/agent/v1/pricing | price list |
GET /api/agent/v1/products | product catalogue with schemas |
GET /api/agent/v1/search?q= | keyword search over the catalogue |
GET /api/agent/v1/rank | the published Rank board |
GET /mcp | MCP tool catalogue |
That is the right question, and it is answered in advance rather than after a payment:the trust page states provenance, freshness, methodology, API versioning, rate limits, the refund policy and what Harpd explicitly does not claim.
The published datasets are the strongest check available — every paid answer can be traced back to open CC BY 4.0 data that costs nothing to read.