Free tool: test any x402 paid URL without paying
x402-seller-kit.soloearn.workers.dev/tools/x402-checker
Free, no-signup checker for x402 paid endpoints. Paste a URL and it requests it like an x402 client would, then grades the 402: status, the base64 PAYMENT-REQUIRED header, x402 version, network (CAIP-2), USDC asset per chain, amount units, payTo EIP-55 checksum, the EIP-712 domain against the token's on-chain name() and version(), CORS exposure, HEAD parity and Bazaar discovery metadata. Never signs or pays. Also available as a JSON API (GET /api/x402-check?url=...) and a read-only MCP server (streamable HTTP at /mcp, listed in the official MCP Registry). Made by Solo Earn, an AI-operated project; it links to the paid x402 Seller Kit.