21 pay-per-call APIs for AI agents — blockchain data, web scraping, ZK proof verification, QR/diagram/OG-image rendering, LLM chat, gift cards. Settled in USDC on Base via the x402 payment protocol. No accounts, no API keys: agents pay per request via the x402 protocol. x402 Payment Protocol Pay-per-call MCP. No accounts. No logins. No keys. 21 tools on Base via the Coinbase CDP x402 facilitator. Agents pay per request in USDC — settled on-chain in seconds. No API keys to provision, no subscriptions to manage. 21 Tools live $0.002 Starting price <2s Response time USDC on Base How it works The x402 protocol turns HTTP 402 Payment Required into an onchain payment flow. 1 Agent reads metadata GET the endpoint. Receive an OpenAPI spec + x402 payment details (payTo, amount, asset, network). 2 Sees...

Verify a NIP-98 Nostr HTTP auth event (kind 27235). Stateful replay protection: each event id can only be verified once. Returns the signer pubkey. Part of the x402 Gateway — $0.002 per call, settled in USDC on Base. No accounts, no API keys: agents pay per request via the x402 protocol. How payment works Send a POST to https://x402.freeq.one/tools/wallet_verify_nostr without a payment header and the API replies 402 Payment Required with an x402 challenge (payTo address, USDC amount, Base network). A paying agent signs the USDC payment and retries with the X-PAYMENT header — settlement is verified on-chain in seconds and the API response returns with an X-PAYMENT-RESPONSE receipt. Example call curl -X POST https://x402.freeq.one/tools/wallet_verify_nostr \ -H "Content-Type: application/json" \ -d '{"items":[{"proof":{"merkleTreeDepth":20,"merkleTreeRoot":"0x1","nullifier":"0x1","mes...

Get the live price of a token by symbol (e.g. ETH, USDC, MATIC). Returns current price, 24h change, and market cap. Part of the x402 Gateway — $0.002 per call, settled in USDC on Base. No accounts, no API keys: agents pay per request via the x402 protocol. How payment works Send a GET to https://x402.freeq.one/tools/token_price without a payment header and the API replies 402 Payment Required with an x402 challenge (payTo address, USDC amount, Base network). A paying agent signs the USDC payment and retries with the X-PAYMENT header — settlement is verified on-chain in seconds and the API response returns with an X-PAYMENT-RESPONSE receipt. Example call curl https://x402.freeq.one/tools/token_price?param={value} Browse every pay-per-call API on the all APIs page , or inspect the machine-readable service card and OpenAPI spec .

Scan recent blocks for large ETH transfers involving an address. Filter by direction (in/out/both) and threshold. Part of the x402 Gateway — $0.002 per call, settled in USDC on Base. No accounts, no API keys: agents pay per request via the x402 protocol. How payment works Send a POST to https://x402.freeq.one/tools/whale_alerts without a payment header and the API replies 402 Payment Required with an x402 challenge (payTo address, USDC amount, Base network). A paying agent signs the USDC payment and retries with the X-PAYMENT header — settlement is verified on-chain in seconds and the API response returns with an X-PAYMENT-RESPONSE receipt. Example call curl -X POST https://x402.freeq.one/tools/whale_alerts \ -H "Content-Type: application/json" \ -d '{"{param}": "{value}"}' Browse every pay-per-call API on the all APIs page , or inspect the machine-readable service card and OpenAPI spec .

Verify an ed25519 Solana wallet signature over a message containing a Nonce line. Consumes the nonce — one verification per nonce. Returns the signer pubkey. Part of the x402 Gateway — $0.002 per call, settled in USDC on Base. No accounts, no API keys: agents pay per request via the x402 protocol. How payment works Send a POST to https://x402.freeq.one/tools/wallet_verify_solana without a payment header and the API replies 402 Payment Required with an x402 challenge (payTo address, USDC amount, Base network). A paying agent signs the USDC payment and retries with the X-PAYMENT header — settlement is verified on-chain in seconds and the API response returns with an X-PAYMENT-RESPONSE receipt. Example call curl -X POST https://x402.freeq.one/tools/wallet_verify_solana \ -H "Content-Type: application/json" \ -d '{"items":[{"proof":{"merkleTreeDepth":20,"merkleTreeRoot":"0x1","nullifier":"0x1...

Verify a Sign-In-With-Ethereum (EIP-4361) signature. Stateless paid oracle: checks the signature against the message and returns the wallet address + chainId. Never mints sessions or consumes nonces. Get a checksummed address first via wallet_checksum. Part of the x402 Gateway — $0.002 per call, settled in USDC on Base. No accounts, no API keys: agents pay per request via the x402 protocol. How payment works Send a POST to https://x402.freeq.one/tools/wallet_verify_siwe without a payment header and the API replies 402 Payment Required with an x402 challenge (payTo address, USDC amount, Base network). A paying agent signs the USDC payment and retries with the X-PAYMENT header — settlement is verified on-chain in seconds and the API response returns with an X-PAYMENT-RESPONSE receipt. Example call curl -X POST https://x402.freeq.one/tools/wallet_verify_siwe \ -H "Content-Type: application/json" \ -d '{"items":[{"proof":{"merkleTreeDe...