Vercel App Mpp

Vercel App Mpp

Vercel App Mpp is the public gateway for the Machine Payments Protocol (MPP), a stablecoin-based payment layer for AI agents and other automated clients. Hosted at https://mpp-gateway.vercel.app/, the gateway sits in front of more than forty third-party APIs and lets a client pay per request with a Tempo stablecoin instead of holding an API key for each upstream service.

The flow is built around HTTP 402 Payment Required. A client makes a normal HTTP 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 then signs and settles the payment automatically, the gateway proxies the call to the upstream API, and the client receives the response together with a signed Payment-Receipt. The end result is that an AI agent can call Stripe, GitHub, Twilio, Plaid, Massive (stocks) and Stripe Climate without ever holding a secret API key.

The gateway currently exposes 88 endpoints across 11 categories and 5 live services. Stock lookups, market status and tickers come from Massive; balance and payment data come from Stripe; SMS comes from Twilio; bank balances come from Plaid; carbon-removal orders come through Stripe Climate; repo and user data come from GitHub. Each endpoint lists its price in USD (often fractions of a cent for read calls, a cent or two for write calls). The site publishes an llms.txt and an All Routes page so AI agents can discover the available 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 storing API keys. 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.