x402lint — scan, check, improve, ship

Lint your x402 listing before agents skip it.

25 read-only checks against your live origin — the 402 handshake, your agent docs, your directory standing — return an A–F grade with per-check evidence and a one-line fix for each finding. SSL Labs, for x402 sellers.

https://

Free grade lookup and full report. An always-fresh scan is a paid x402 call — no signup, no keys here.

x402lint report

api.example.dev

B
SCORE82 / 100
PASS

19

WARN

4

FAIL

2

P5head-no-settle
S5bazaar-post-extensions
P2x402-challenge

sample report · your grade varies

// THE MARKET TRUTH

Most x402 listings are silently broken. Agents just move on.

~2,900

x402 origins registered

~127

made a sale last month

the rest

silently broken or invisible

There is no error message when an agent skips you — it just picks the next origin that answers the handshake cleanly. x402lint finds the exact reasons, before your buyers do:

P2Dead 402s — a paid route that never returns a valid x402 challenge.
P8Oversized CDP descriptions that get truncated or rejected on listing.
S5Missing Bazaar POST extensions, so paid POSTs never get discovered.
S3Free ops missing security: [], so x402scan mis-indexes them.
P5No-settle guard broken — a garbage payment header served a 200.
D1Not registered on x402scan at all, so no agent can find you.

// 25 CHECKS · v2026-07-25.1

What we check

Every check is read-only and versioned. We fetch your live surfaces — never send a real payment (the only payment-ish probe is a literal garbage header) — and grade three categories.

Protocol & payment surface

8 checks

402 challenge validity, accepts[] schema, price integrity, HEAD-does-not-settle, and payment-header correctness.

Discovery & agent docs

12 checks

OpenAPI x402 conventions, security schemes, Bazaar extensions, .well-known surfaces, llms.txt, agent-card, robots, and favicon.

Ecosystem standing

5 checks

Registration/freshness on x402scan, recent on-chain settlement, trust tier, and x402.org presence.

25 checks across 3 categories — the full per-check findings and fixes are free to read in the cached report; pay only to force an always-fresh re-scan.

// DIRECTORY

Previously scanned

The recently-scanned archive of graded origins (5156 total). Branding is auto-collected and unverified.

Grades measure x402 protocol conformance only — not legitimacy or safety. A well-built scam can score an A. Always do your own diligence before paying any service.

gitbeacon

api.gitbeacon.dev

A

Protocol 100·Docs 100·Standing 98

gitBeacon — GitHub trend intelligence for AI agents. A daily scan of trending new GitHub repos, LLM-analyzed into a structured digest (titl…

✓ Verified owneron x402scan

orcatrace

api.orcatrace.dev

A

Protocol 96·Docs 100·Standing 98

OrcaTrace — Polymarket intelligence on x402. Track smart money, see what others miss. Real-time prediction-market signals across the full P…

✓ Verified owneron x402scan

demandex

api.demandex.dev

A

Protocol 90·Docs 100·Standing 98

Demandex mines community demand for physical products. It classifies Reddit complaint and intent posts across 82 communities into demand si…

✓ Verified owneron x402scan

vindex

api.vindexapi.dev

A

Protocol 90·Docs 100·Standing 98

Vehicle Intelligence for AI agents. Pay per call with x402 (USDC on Base) to decode any 17-char VIN with its original factory new-vehicle w…

✓ Verified owneron x402scan

x402lint

api.x402lint.dev

A

Protocol 92·Docs 100·Standing 98

x402lint scans an x402 seller origin end-to-end: 402 challenge validity, accepts[] schema, price integrity, OpenAPI x402 conventions, agent…

✓ Verified owneron x402scan

signalis

api.signalis.dev

A

Protocol 100·Docs 100·Standing 98

Signalis — global intelligence, real-time awareness. Two surfaces on x402: (1) Master Intelligence — a cross-source synthesis produced ever…

✓ Verified owneron x402scan

Moltalyzer

api.moltalyzer.xyz

A

Protocol 96·Docs 100·Standing 99

Moltbook community intelligence for AI agents: hourly digests of what the AI-agent community is discussing, plus a Viral Advisor that score…

✓ Verified owneron x402scanx402.org

Isocast

api.isocast.dev

A

Protocol 86·Docs 100·Standing 98

Agents pay per-signal bundles via x402 and get pushed (Telegram) the instant a city's daily-high temperature crosses into a new Polymarket…

✓ Verified owneron x402scan

FastAPI

ttww-backend-1761811693.fly.dev

B

Protocol 90·Docs 67·Standing 98

on x402scan

Express on Vercel

express-indol-ten.vercel.app

F

Protocol 26·Docs 74·Standing 98

on x402scan

Cybercentry Web Application Verification - x402

x402-cybercentry-web-application-verification.up.railway.app

B

Protocol 90·Docs 74·Standing 98

on x402scan

COBOL Copybook & Mainframe Modernization API

cobol-modernize-api.fly.dev

B

Protocol 96·Docs 67·Standing 98

Tools for mainframe modernization projects: convert COBOL copybooks to JSON schema, decode real EBCDIC/packed-decimal mainframe records int…

on x402scan

G2E Agent API

api.g2e.io

B

Protocol 90·Docs 74·Standing 98

REST API for the Gamble to Earn platform — the universal interface for all agent interactions. Any agent that can make HTTP requests can re…

on x402scan

x402flip | First coinflip on x420

x402flip.xyz

F

Protocol 5·Docs 74·Standing 98

Flip it or leave it. x402 decides

on x402scan

Yield.xyz MCP

mcp.yield.xyz

B

Protocol 92·Docs 73·Standing 98

DeFi yield discovery & execution across 80+ networks. Free read tools (yields, risk, validators, networks, providers, action/transaction st…

on x402scan

Twitter X Verification — Verify Follows via API | x402scan

x402-xapi.onrender.com

F

Protocol 26·Docs 74·Standing 98

Twitter X Verification instantly checks if one Twitter (X) account follows another through API — perfect for airdrop tasks, campaign valida…

on x402scan

x402 Twitter API

twitter-x402.xyz

F

Protocol 5·Docs 74·Standing 98

Pay-per-use access to Twitter API endpoints with x402 micropayments

on x402scan

token-1wp9hkzjd-blus-projects-bb43daa9.vercel.app

token-1wp9hkzjd-blus-projects-bb43daa9.vercel.app

F

Protocol 26·Docs 77·Standing 98

on x402scan

AnchorRegistry API

api.anchorregistry.ai

B

Protocol 96·Docs 63·Standing 98

Register any digital artifact and receive permanent, verifiable, on-chain proof of authorship. One payment. No expiry. Verifiable by any hu…

on x402scan

x402.getunreel.ai

x402.getunreel.ai

F

Protocol 26·Docs 67·Standing 98

on x402scan

x402.autoamm.link

x402.autoamm.link

F

Protocol 26·Docs 77·Standing 98

on x402scan

Mart.fun - X402 Agent Marketplace

api.mart.fun

F

Protocol 5·Docs 74·Standing 98

Build, deploy & monetize AI agents on Solana with USDC micropayments.

on x402scan

x402.unreel.ai

x402.unreel.ai

F

Protocol 5·Docs 74·Standing 98

on x402scan

Silverback

x402.silverbackdefi.app

F

Protocol 26·Docs 74·Standing 98

Silverback is autonomous DeFi infrastructure for the agent economy. We provide intelligence services (swap routing, liquidity analysis, yie…

on x402scan

dev-api.rencom.ai

dev-api.rencom.ai

F

Protocol 5·Docs 74·Standing 98

on x402scan

Recoup API

recoup-28x9ye415-recoupable-ad724970.vercel.app

F

Protocol 26·Docs 77·Standing 98

AI agents made for the music industry.

on x402scan

Price Oracle

price-oracle-production-9e7c.up.railway.app

F

Protocol 26·Docs 77·Standing 98

Multi-chain token price feeds via x402 micropayments

on x402scan

ETHMumb.ai

ethmumbai-three.vercel.app

B

Protocol 90·Docs 75·Standing 98

Transform photos into ETHMumbai avatars. Generate and share on Farcaster.

on x402scan

Transaction Simulator - x402 Agent

transaction-simulator-production.up.railway.app

F

Protocol 26·Docs 77·Standing 98

Preview transaction outcomes before execution - gas costs, asset changes, and failure prediction across 7 EVM chains

on x402scan

Talk to Jesus

jesuschrist.sh

F

Protocol 26·Docs 75·Standing 98

Have a conversation with Jesus using AI. Get spiritual guidance and wisdom.

on x402scan

// PRICING

Grades are free. Fresh scans cost cents.

Look up any grade and read the full cached report for free. Force an always-fresh scan for a few cents in USDC over x402 — plus a machine tier for agents: bulk directory export and a change feed. No signup and no API keys.

Status lookup

FREE

no payment ever

Grade, score, and pass/warn/fail counts for any prior scan. The cold-email payload.

GET /v1/status

Cached full report

FREE

no payment ever

The complete per-check findings and fixes for any recently-scanned origin (<24h cache).

GET /v1/report

Change feed

$0.03

per call · USDC via x402

Machine tier: directory changes since a cursor — new, grade_changed, and rescanned events.

GET /v1/changes

Fresh conformance scan

main

$0.05

per call · USDC via x402

Force an always-fresh run of every check against your origin, bypassing the cache — A–F grade with per-check evidence and fixes.

POST /v1/scan

Directory export

$0.10

per call · USDC via x402

Machine tier: the full graded directory as one dump, with grade history per origin.

GET /v1/directory/export

// FOR AGENTS

Everything is machine-readable

Agents: start at llms.txt on the API host. No docs portal, no sandbox keys, no signup — the challenge tells you the price and where to pay. There is a machine tier too: a bulk directory export and a change feed for agents that track the graded directory.

llms.txtapi.x402lint.dev/llms.txtllms-full.txtapi.x402lint.dev/llms-full.txtopenapi.jsonapi.x402lint.dev/openapi.json.well-known/x402api.x402lint.dev/.well-known/x402.well-known/agent-card.jsonapi.x402lint.dev/.well-known/agent-card.jsondiscoveryapi.x402lint.dev/discovery