x402-x402fix

x402fix: x402 endpoint doctor for sellers (probes a paid x402 URL unpaid and grades it A-F with paste-ready fixes: 402 on GET/HEAD/POST, CORS, v2 header + v1 body, CAIP-2, USDC asset + EIP-712 domain, Solana feePayer, Bazaar schema, multichain drift, CDP validate verdict, generated Bazaar block) + MCP server

Browse source · x402-x402fix.tar.gz · x402-x402fix.bundle
commit 7e5384f · 7e5384fa991ddfd46a029a0adcf937af437dc842
Clone: git clone https://agentgate-source.pages.dev/x402-x402fix/x402-x402fix.git (branch main, commit 7e5384fa991ddfd46a029a0adcf937af437dc842) or

curl -O https://agentgate-source.pages.dev/x402-x402fix/x402-x402fix.bundle && git clone x402-x402fix.bundle x402-x402fix

Mirror note: this repo used to live on GitHub under the agentgate-builder account (suspended Oct 21, 2026). Links in the README below were rewritten for this mirror: source links point here, GitHub Pages demos to this page (this repo has no demo), npx github: installs to the tarball on this site, and CI badges became a "tests passing locally" note. The tarball, bundle and raw files are unmodified.

x402fix: x402 endpoint doctor

Point x402fix at any paid x402 URL and it tells you, in order of severity, what will break payments or keep the route out of the Bazaar / x402scan, and how to fix each problem. It probes the route without paying: GET, HEAD, an empty POST, POST {} and a CORS preflight. Then it grades the route A to F.

Transport: 402 on GET, HEAD and empty POST; CORS preflight; Access-Control-Expose-Headers: PAYMENT-REQUIRED; cacheable 402s; redirects; auth walls; latency.
x402 v2: PAYMENT-REQUIRED header; resource.url; CAIP-2 networks; amount given as a string of atomic units; canonical USDC asset; the EIP-712 domain (extra.name and extra.version) for each chain; payTo format; Solana extra.feePayer; maxTimeoutSeconds.
x402 v1: JSON body; maxAmountRequired; network names; whether v1 and v2 terms agree.
Bazaar: extensions.bazaar info and schema. It validates info against schema (JSON Schema 2020-12), flags external $ref and old drafts, and checks method and input/output consistency.
Multichain: price drift across networks, duplicate entries, networks the CDP facilitator doesn't settle, and which of Base, Polygon, Arbitrum One and Solana you accept.
Check tier extras: the CDP facilitator's own validate verdict and Bazaar index status, payee checks (EVM contract vs wallet, whether the Solana USDC token account exists, CounterpartyCheck screening), drift between /openapi.json and /.well-known/x402, a generated, self-validated extensions.bazaar block, and a multichain accepts snippet for Hono, Express or Next.

Live API: https://api.youraitools.co/x402fix (origin: https://x402fix.agentgate.workers.dev)

Route	Price (USDC)	Returns
`GET /v1/preview?url=`	free, 10/min	grade, score, status, counts, detected versions and networks
`GET\|POST /v1/lite?url=`	$0.005	every check plus a numbered fix list
`GET\|POST /v1/check?url=&framework=hono`	$0.02	lite + CDP verdict, payee checks, docs drift, generated Bazaar block and accepts
`GET\|POST /v1/site?url=https://origin`	$0.05	finds up to 8 paid routes from `/.well-known/x402` and `/openapi.json`, grades each, checks doc drift

Payment: x402 v2 or v1, exact USDC on Base, Polygon, Arbitrum One or Solana. Prepaid credits (Authorization: Bearer) are also accepted, via https://api.youraitools.co/credits.

MCP

Remote: https://api.youraitools.co/x402fix/mcp (tool check_x402_endpoint, free preview)
stdio: npx -y @agentgate-builder/x402fix. Set X402FIX_X402_PRIVATE_KEY to a Base wallet key holding a little USDC, and it pays for check reports ($0.02 each).
Docker: docker build -t x402fix-mcp . && docker run -i --rm x402fix-mcp

CI

curl -s "https://api.youraitools.co/x402fix/v1/preview?url=https://your.api/v1/paid" | jq -e '.status != "broken"'

Notes

Probes are unpaid and never send payment headers. Private, loopback and link-local hosts are refused, and ports are limited to 80, 443, 8080, 8443, 3000, 8000 and 8787.
Fixes are suggestions. A passing grade does not guarantee listing or settlement.

Develop: npm test; npm start (Node, port 8795); npx wrangler deploy. MIT.

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