Web tools an AI agent pays for per call in USDC, no API key (x402+MCP)
HTTP 402 Payment Required for autonomous agent micropayments in USDC.

HTTP 402 finally has a real use case: pay-per-file via gasless USDC transfers.
Crypto developers, Web3 apps needing micropayment infrastructure, users seeking account-free file sharing
Filebase · Web3.Storage · Pinata
The idea: HTTP 402 ("Payment Required") has existed since 1997 but was never really used. The x402 protocol (https://x402.org) finally gives it a real implementation — server responds 402 with a payment challenge, client signs a gasless USDC transfer (EIP-3009), facilitator settles on-chain, client retries with a payment header. No API keys, no OAuth, no accounts.
x402drop uses this as the payment layer for temporary file storage:
- Connect wallet (SIWE), drag-and-drop files (up to 5 GB each, 10 GB per drop) - Pick a duration (1 hour to 90 days), see a quote ($0.0003/MB/day, $0.01 minimum) - Sign one USDC transfer — gasless, facilitator pays gas - Get a share link — recipients download for free, no wallet needed - Files auto-delete from R2 within ~15 minutes of expiry via cron
There's also an Agent API — AI agents and scripts can create drops programmatically using the same x402 payment flow. No API key, the 402 payment header is the auth.
Stack: Next.js (App Router), SIWE + RainbowKit, Drizzle ORM + Neon Postgres, Cloudflare R2, @x402/next, Vercel.
Pricing is deterministic: max(fileSizeMB × durationDays × 0.0003, 0.01) per file.
Known limitations: - Mainnet only (no testnet mode yet) - USDC only (no ETH or other tokens) - No email notifications for expiry warnings
The part I find most interesting technically is using HTTP 402 as a real protocol primitive rather than a payment wall gimmick. The facilitator model means the payer never touches gas, and the whole flow is just HTTP request → 402 → signed header → 200.
Live at https://x402drop.com. Docs at https://x402drop.com/docs.
Happy to answer questions about the x402 protocol implementation or the architecture.
HTTP 402 Payment Required for autonomous agent micropayments in USDC.
Escrow refunds for failed AI API calls — Austin Griffith and Ethereum Foundation endorse it.
x402 micropayments are clever, but the API is a thin wrapper around existing crypto data sources.
Three-line middleware for x402 payments—Stripe for AI agents, but crypto-native.
Infrastructure for an agent economy that doesn't really exist yet.
Well-built middleware betting on an agent payment economy that doesn't exist yet.