x402market documentation — list and discover paid APIs

x402market is a registry of pay-per-call services for AI agents. Sellers publish a manifest; the worker verifies it against a live 402 challenge and lists it. Buyers (often agentpay wallets) read listings and quotes without a wallet.

Why a registry matters

An agent can't browse a website, compare pricing pages, or sign up for a trial. It needs machine-readable answers to three questions:

1. What tools exist and what do they do? → manifest
2. What does a call cost right now? → live 402 quote
3. Where do I pay? → payTo address and network

Everything in x402market answers those three questions in JSON.

Publishing a service

You need an x402-compatible endpoint that returns 402 with a PAYMENT-REQUIRED header on unpaid calls. The easiest paths:

• x402 Gateway — register an upstream URL and get a hosted /g/<slug>/<tool> endpoint. No code.
• Self-hosted — use the Seller Kit pattern (see github.com/auxon) to deploy a Worker that challenges and settles directly.

Then submit the manifest URL:

curl -s -X POST https://entangleit.com/api/x402market/services \
  -H 'content-type: application/json' -d '{
    "manifestUrl": "https://x402-gateway.richard-hein.workers.dev/g/weather-oracle/manifest",
    "name": "Weather Oracle",
    "tagline": "Pay-per-call forecasts",
    "description": "Global forecasts, 20 sats per call.",
    "ownerContact": "[email protected]"
  }'

Verification happens synchronously: the worker fetches the manifest, checks the shape (base URL, network, tools), then probes a paid tool and requires a real 402 with decodable requirements. Listings that fail verification are rejected with the reason (422).

Registry API

| Route | Auth | Purpose | | --- | --- | --- | | GET /api/x402market/services | — | Verified listings. Filters: q, network, sort=new\|tools, limit | | GET /api/x402market/services/:id | — | Listing detail (increments views) | | POST /api/x402market/services | — | Publish a manifest (verified before insert) | | GET /api/x402market/quote?service=&tool= | — | Live 402 requirements for one tool, proxied from the seller |

Example quote response shape:

{
  "quote": {
    "serviceId": "s_…",
    "tool": "forecast",
    "satoshis": 20,
    "payTo": "1…",
    "network": "bsv:mainnet",
    "resource": "https://…/forecast?city=YYZ"
  }
}

No wallet is needed to quote — that's the point. Agents price the call before deciding to spend.

What agents do with it

An agentpay wallet exposes the registry through MCP:

• list_services reads verified listings.
• service_quote proxies the live 402 challenge.
• pay_service settles and returns the seller's result in one call.

The same tools work directly against this API for agents that don't use agentpay.

Listing rules

• The manifest URL must be https://.
• The paid tool must challenge with a decodable PAYMENT-REQUIRED header at verification time.
• Free tools are allowed alongside paid ones and are labeled.
• Listings that stop challenging, or whose seller disappears, can be removed or paused; the directory only shows verified entries.
• Credentials are never part of a listing — payTo and prices are public by design.

FAQ

Does listing cost anything?

No. Listing is free; the gateway that powers hosted listings has a Free tier and a $9/mo Pro tier for volume.

How is this different from an API directory?

Directories list docs. x402market lists prices and payment addresses verified against a live challenge, so the next step is a paid call, not a signup.

Can I update a listing?

Update the gateway service and relist it, or resubmit the manifest — verification runs again on every submission.

How do I get featured?

Featured placement is curated. The strongest signal is a fast, reliable endpoint with clear tool descriptions and honest pricing.