# testmpp

> testmpp.com is the public test endpoint for MPP (Machine Payments Protocol) agent payments. Agents and developers send a test payment on Tempo testnet (chain 42431, pathUSD test stablecoin) and get an echo back. The $0.01 is faucet test-money — testing costs nothing real. A mainnet verification endpoint (real $0.01 per test) is on the roadmap.

MPP is the open machine-to-machine payment protocol launched by Stripe and Tempo (March 2026), formalizing HTTP 402 Payment Required via the IETF draft draft-ryan-httpauth-payment-01. It is backward-compatible with x402.

## Endpoints

- [GET /health](https://testmpp.com/health): liveness + network info
- [ANY /echo](https://testmpp.com/echo): free echo — returns your method, headers, and body as JSON; no payment needed
- [ANY /pay/echo](https://testmpp.com/pay/echo): MPP-paid echo — returns a spec-correct 402 challenge (WWW-Authenticate: Payment, method=tempo, intent=charge, $0.01 pathUSD on Tempo testnet). Settlement verification is in progress; presented credentials currently receive an honest 501.

## How to test a payment

- Inspect a challenge: `curl -i https://testmpp.com/pay/echo`
- Pay with the official CLI: `npx mppx account create && npx mppx account fund && npx mppx https://testmpp.com/pay/echo`
- Free Tempo testnet funds: POST https://docs.tempo.xyz/api/faucet

## Docs

- [Endpoint reference](https://testmpp.com/docs): challenge format, network details, client examples
- [MPP spec (IETF draft)](https://datatracker.ietf.org/doc/html/draft-ryan-httpauth-payment-01)
- [mppx SDK](https://github.com/wevm/mppx)