# MPP (Machine Payments Protocol)

Publishing an API's prices in its OpenAPI document, so an agent knows what a paid endpoint costs before it calls one.

**[Commerce](/docs/commerce)** · watched, not scored

It is the first agent-payment protocol whose terms sit in a document a crawler can read without attempting a payment: the same /openapi.json this container already fetches, annotated with x-payment-info offers. An agent that reads a broken offer plans against a price that is not real, and an operation priced without a 402 response leaves it no way to pay.

## Why we do not score it

The discovery extension is a draft in the specification repository, not a submitted Internet-Draft, and the draft itself makes discovery OPTIONAL because the runtime 402 challenge is always authoritative. Score it once the extension is submitted and stable and more than one organisation serves a discovery document.

## Adoption

**Early pilots** (L1) — protocol L2 / discovery documents L1

Named early adopters exist, behind flags or trials. Nothing has been independently measured yet. Direction of travel: ▲ rising, as of 2026-08-26.

Co-authored by Stripe and Tempo and published on 2026-03-18, with Stripe accepting cards and stablecoins through it and Cloudflare documenting it for agents. A Lumar probe on 2026-08-26 found one live discovery document: Parallel's gateway serves three payable operations, each carrying a conformant x-payment-info offer and a 402 response.

| Adopter | Depth | Evidence |
|---|---|---|
| Stripe (payment provider: cards via shared payment tokens, plus stablecoins) | production | [docs.stripe.com](https://docs.stripe.com/payments/machine/mpp) |
| Parallel (parallelmpp.dev; discovery document verified by probe) | production | [docs.parallel.ai](https://docs.parallel.ai/integrations/agentic-payments) |
| Cloudflare (documented for its Agents platform) | announced | [developers.cloudflare.com](https://developers.cloudflare.com/agents/tools/payments/mpp/) |

## Specifications

| Document | Revision | Kind |
|---|---|---|
| [Service Discovery for HTTP Payment Authentication](https://github.com/tempoxyz/mpp-specs/blob/main/specs/extensions/draft-payment-discovery-01.md) | draft-payment-discovery-01 | specification |
| [The "Payment" HTTP Authentication Scheme](https://datatracker.ietf.org/doc/draft-ryan-httpauth-payment/) | draft-ryan-httpauth-payment-01 | specification |
| [MPP documentation](https://mpp.dev) | living document | guidance |

Last re-read against the published documents: 2026-08-26.