x402 tools
Free x402 developer tools
Small, browser-based utilities for working with the x402 protocol (HTTP 402 Payment Required). No signup, no backend — everything runs locally in your browser.
402 Payload Parser
Paste an X-PAYMENT header or a 402 Payment Required response and decode it to readable JSON — scheme, network, amount, payer, and pay-to broken out.
Open tool402 Header Generator
Build a valid 402 challenge response (accepts[]) or encode an X-PAYMENT request header, with automatic atomic-unit amount conversion and copy-paste code.
Open toolAbout x402
x402 is an open protocol built on the HTTP 402 Payment Required status code. A server responds with 402 and a price; the client (often an autonomous AI agent) pays on-chain — typically USDC on Solana or an EVM chain — and retries with an X-PAYMENT header proving payment. These tools help you read and write the payloads on both sides of that handshake while you build and debug an integration. Learn more in our guide to x402, or see how 402.report tracks what your agents actually pay across every domain.