MPP Protocol
MPP explained: Stripe and Tempo's Machine Payments Protocol for agent payments, with one-off charges, metered sessions, stablecoins and cards, and how it compares to x402.
What is MPP?
The Machine Payments Protocol (MPP) is Stripe and Tempo’s open standard for agents paying for services. It launched on March 18, 2026 with the Tempo mainnet. Visa contributed a card specification on day one, and more than 100 services were listed in the directory at launch.
Like x402, MPP starts with an HTTP 402 challenge. The difference is that MPP is built for many payments over one relationship, not one payment per request.
How It Works
Every MPP payment follows the same three steps: challenge, credential, receipt. On top of that, MPP defines a few payment intents:
- Charge: a one-off payment, close to x402’s
exactscheme. - Session: the agent pre-funds a channel and pays with off-chain vouchers. Many small payments settle as one transaction. It has been described as “OAuth for money”.
- Subscription: recurring fixed payments.
- Streaming: per-token billing over server-sent events, which fits LLM APIs.
Payment Methods
MPP is rail-agnostic. Today it supports:
- Stablecoins on Tempo, Solana, Stellar, EVM chains and others
- Cards and BNPL through Stripe’s Shared Payment Tokens
- Lightning, XRPL and other methods
MPP vs x402
| x402 | MPP | |
|---|---|---|
| Model | One payment per request | Charges, sessions, subscriptions, streaming |
| Rails | Stablecoins | Stablecoins, cards, BNPL, more |
| Governance | x402 Foundation (Linux Foundation) | Stripe and Tempo |
| Traction | About 110M transactions, about $15M adjusted volume (to Apr 2026) | About 115K transactions, about $25K in first weeks |
They are not rivals so much as neighbors. MPP’s EVM method supports x402 exact flows, and one endpoint can serve both kinds of client. Pick based on your billing model. See our protocol comparison for the full picture.
Our MPP Services
- Billing model design: per-request vs session vs streaming pricing for your API
- Integration: MPP alongside x402 on one endpoint
- Security audit: session voucher handling, replay and spend controls
Last updated October 9, 2026
Frequently Asked Questions
What is the Machine Payments Protocol (MPP)?
MPP is an open protocol for machine and agent payments, co-authored by Stripe and Tempo and launched on March 18, 2026 alongside the Tempo mainnet. Like x402 it uses an HTTP 402 challenge, but it is rail-agnostic: the same flow can settle in stablecoins, cards or other methods.
How is MPP different from x402?
x402 settles each request as its own payment. MPP adds sessions: an agent pre-funds a channel and pays with off-chain vouchers that are settled together later, which suits high-frequency metered use such as per-token billing. The two are compatible: MPP's EVM method supports x402 exact payments, and one endpoint can serve both kinds of client.
Can MPP charge cards?
Yes. Through Stripe, MPP supports cards and buy-now-pay-later via Shared Payment Tokens, as well as stablecoins. Visa published a card specification and SDK for MPP on launch day. Stripe's minimums are $0.50 for card payments and 0.01 USDC for stablecoins.
How much volume does MPP handle?
It is very early. Visa's onchain analysis counted about $25,000 across roughly 115,000 transactions in MPP's first weeks. Treat it as a fast-moving protocol with serious backers rather than a proven high-volume rail.
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