MPP - Machine Payments Protocol

MPP is an open protocol (co-authored by Tempo and Stripe) that standardizes HTTP 402 Payment Required for machine-to-machine payments. Clients pay in the same HTTP request - no accounts, API keys, or checkout flows needed.

The core protocol spec is submitted to the IETF as the Payment HTTP Authentication Scheme.

When to Use

• Building a paid API that charges per request
• Adding a paywall to endpoints or content
• Enabling AI agents to pay for services autonomously
• MCP tool calls that require payment
• Pay-per-token streaming (LLM inference, content generation)
• Session-based metered billing (pay-as-you-go)
• Accepting stablecoins (Tempo), cards (Stripe), or Bitcoin (Lightning) for API access
• Building a payments proxy to gate existing APIs (OpenAI, Anthropic, etc.)

Core Architecture