Vercel App Mpp

Vercel App Mpp is the public gateway for the Machine Payments Protocol (MPP), a stablecoin-based payment layer that lets AI agents and other automated clients pay per request with a Tempo stablecoin instead of holding API keys for each upstream service. Hosted at https://mpp-gateway.vercel.app/, the gateway sits in front of more than forty third-party APIs and currently exposes 88 endpoints across 11 categories and 5 live services.

The flow is built around HTTP 402 Payment Required. A client makes a normal request to an MPP endpoint; if payment is required the gateway returns a 402 with the price and payment instructions. A Tempo CLI running on the client signs and settles the payment, the gateway proxies the call to the upstream API, and the client receives the response plus a signed Payment-Receipt. The result is that an AI agent can reach Stripe, GitHub, Twilio, Plaid, Massive (stocks) and Stripe Climate without ever storing a secret API key.

Each endpoint lists its price in USD — often fractions of a cent for read calls and a cent or two for write calls. The site publishes an llms.txt and an All Routes page so AI agents can discover endpoints programmatically. Vercel App Mpp is positioned for AI agents, automation scripts, MCP servers and developer tooling that needs to reach paid third-party APIs without API key management.

The gateway runs on Vercel's edge network, charges transparent per-request prices, and ships with a public GitHub repository. It is one of the first concrete implementations of machine-to-machine stablecoin payments for general API access.