Why did my x402 payment retry fail in the browser?
Use a locally saved HAR (HTTP Archive) to triage 402 challenge visibility, 400/422 before payment, payment-header retries, and CORS preflight. Unlike a curl-only test, this examines the browser's observed sequence. It does not make requests, execute payments or assert successful USDC settlement.
PAYMENT-SIGNATURE, cookies, authorization headers, signed requests and personal data. Analyze only files you control. This page processes the file strictly inside your browser and never sends it to us. Never email or publish the original HAR. Exported findings exclude headers, URLs and payloads.Run a local diagnostic
In Chrome DevTools → Network, reproduce one authorized problem on your own endpoint, then export HAR (with sensitive data removed when possible). Captures can omit preflights. This page accepts at most 2 MB of HAR JSON with 400 entries; larger traces should be trimmed locally.
What this tool can — and cannot — establish
- Can: highlight a missing or hidden
PAYMENT-REQUIREDresponse header, an observed OPTIONS mismatch, an unsigned400/422, a signed retry receiving402, and v1/v2 metadata shapes. - Cannot: know whether money reached the payee, whether the quoted USDC asset is authentic, or whether a paid resource was delivered. HTTP 2xx is not a chain receipt. Some CORS requests never appear in a captured HAR.
- Privacy model: no analytics, fetch, SDK, CDN, cookies, localStorage, wallet provider or server-side processing. The analyzer returns authored codes and integer counts only. You can inspect the open-source implementation.
One x402 browser failure, one actionable answer: 5 Base USDC pilot
Use the free diagnostics first; if they resolve your issue, pay nothing. For one endpoint you own or are authorized to test, a 5 native Circle USDC on Base fixed-price pilot can turn one redacted issue into one original reproducible, synthetic-only test fixture and targeted CORS/x402 configuration checklist (not live production deployment). The pilot needs only your browser Origin, expected HTTP method, observed HTTP status, public header names and sanitized findings codes. Do not share a raw HAR, signed payment, token, wallet history, credentials, customer invoice or private endpoint.
- Deliverable: one text report with the failure classification, minimum public-header/server configuration guidance, one synthetic regression fixture, and limits/unknowns. This is transport QA, not a security audit, payment verification or full application fix.
- Commercial boundary: request first, then both parties agree exact scope, acceptance checks, delivery/refund conditions and a native Circle USDC/Base mainnet payment instruction in writing. No payment should be sent before agreement; requesting a quote is free and creates no obligation.
- Privacy: never upload your real HAR or payment signature. If your case requires secrets, access to another party's system, or an unbounded debugging investigation, this fixed-price pilot is unsuitable.
Need a broader one-endpoint integration review?
If the free diagnostic does not resolve your own public, authorized x402 endpoint, request a bounded, synthetic-data-only review with acceptance criteria. Indicative 19 native Base Circle USDC for one endpoint and one reproducible scenario; final price/scope and payment instructions require written confirmation. No seed phrase, private payment payload, secret API key, production invoice or wallet approvals accepted.
Request one-endpoint paid QAFor AI-agent buyers seeking a smaller existing service, the original Soul.Markets seller lists a separate quote-preflight micro-service. Its exact current paid terms are set by that platform, not this page.