x402 Integration on Radius

What this Skill is for

Use this Skill when the user asks to:

• Add x402 payment gating to an API endpoint
• Monetize an API with per-request micropayments
• Build a pay-per-call or pay-per-query service
• Consume or call an x402-protected API
• Sign x402 payment headers (EIP-2612 + Permit2)
• Integrate with an x402 facilitator service
• Understand the x402 HTTP 402 payment flow
• Set up x402 middleware for a server

Not this Skill: For dApp development on Radius (wagmi, Foundry, event watching), use the radius-dev skill. For programmatic on-chain operations from agent code (balance checks, token transfers, contract interaction via wallet libraries), use the radius-agent-ops skill. For getting testnet/mainnet tokens, use the dripping-faucet skill. For direct on-chain payment patterns (pay-per-visit paywalls, streaming payments) that don't use x402 facilitators, see radius-dev's micropayments.md. For platform deployment, hosting, domains, or infrastructure operations, use the relevant deployment skill (for example Cloudflare, Wrangler, Railway) after the x402 endpoint behavior is implemented.

Protocol overview

x402 is an HTTP-native micropayment protocol. Payments happen via off-chain permit signatures settled by a facilitator — no on-chain transaction from the client.