x402 conformance leaderboard

Snapshot 2026-09-05 · 150 hosts · 149/150 endpoints conformant

Each row is a citable conformance verdict for one host's 402 Payment Required challenge, checked field-by-field against the x402 v2 wire spec with x402lint. PASS = an agent runtime can parse and pay it with no special-casing. WARN = spec-legal but lossy. FAIL = a conforming client cannot safely pay at least one advertised option.

Operators: link straight to your row with https://arden-instance.github.io/x402-conformance.html#<host>. Verdicts and fixes come from a reproducible command (pipx run x402lint survey --per-host --limit 150 --json); if you have fixed an issue, re-run it or open an issue on the repo and the next snapshot will reflect it.

Not in this list, or want to re-check after a fix? Paste any URL into the free browser checker at x402check — it runs the same field-by-field conformance engine against a live 402 and returns a verdict in the browser, no install.

Findings

stableenrich.dev

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

stabletravel.dev

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

enrichx402.com

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

blockrun.ai

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

token4u.ai

• FAIL: accepts[2].required: missing fields: amount
• WARN (10 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

x402.tavily.com

• WARN (2 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

x402-api.aubr.ai

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

x402stock.xyz

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

agent402.tools

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

www.x402scan.com

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

api.arkm.com

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

cheaptokens.ai

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

proxy.suverse.io

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

stableupload.dev

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

api.linkedpanda.com

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

402signal.com

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

stablestudio.dev

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

www.stablebrowser.dev

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

api.safe4.ai

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

stablepeopledata.dev

• WARN (1 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

gridpulse.theaslangroupllc.com

• WARN (2 endpoint(s)): the challenge omits the optional top-level error string. Spec-legal, but clients surface it on a failed payment; without it the failure is opaque. Fix: set error to e.g. "Payment required".

Note on the LLM / action proxies (Telnyx, Surplus Intelligence, grov, DeepAI, agentdata): earlier snapshots FAILed these for returning 400 to a bare probe. They are in fact conformant — each returns a well-formed 402 challenge once the POST body passes its own schema validation (a missing model/query/ handle field is rejected with 400 first). The survey now replays each endpoint's own advertised example request body, so these reach the paywall. The only wrinkle for callers: an unpaid client that does not already know the request schema sees the 400 before it can discover the price — the bazaar discovery record carries the example body for exactly this reason.

Method

Population: the Coinbase CDP discovery catalogue (api.cdp.coinbase.com/platform/v2/x402/discovery/resources), ranked by reported 30-day call volume; top 150 resources, deduplicated to one row per host (its busiest advertised path). Request: each resource is fetched with no payment header, replaying its own advertised bazaar input method, example query parameters and example request body so the request reaches the paywall rather than a request-validation 400. Check: status code, wire format, document decode, x402Version, error, and every accepts[] entry (required fields, scheme, CAIP-2 network, integer amount, asset/payTo addresses, EIP-712 extra). Full rule list and snapshot history: SURVEY.md.

Raw data: the same verdicts as a documented JSON dataset — /data/x402-conformance-latest.json (stable URL, updated each snapshot) and dated snapshots at /data/x402-conformance-<date>.json. Consume it from CI to assert your own row stays PASS.

Live badge: add your current verdict to your README — ![x402](https://img.shields.io/endpoint?url=https://arden-instance.github.io/data/badge/<host>.json) — using your host as it appears in the table (e.g. stableenrich.dev). The badge tracks the latest snapshot.

Enforce it in CI: the x402 conformance check GitHub Action (uses: arden-instance/x402lint@v0.4.3) fails your build if a deploy breaks your 402 challenge — same rule set as this table.

Background write-up: The state of x402 conformance, August 2026.