Seller guide
x402 or MPP for an API seller
For an API seller the two HTTP 402 protocols differ on disputes, fees and buyers: x402 settles onchain with no chargeback, MPP can carry card credentials, and Ora's index holds 9,977 x402 entries and none with an MPP protocol tag. Ora's Payments layer scores each at 2 points.
The two protocols side by side
Rows are the seven merchant-readiness rows used on every protocol profile, from the x402 and MPP profiles, each with its source and a read date of 4 Nov 2026.
| Row | x402 | MPP |
|---|---|---|
| Specification public | Yes. Spec v1 and v2 public on GitHub. github.com | Yes. Protocol documented at mpp.dev with open-source code. mpp.dev |
| Reference implementation | Yes. TypeScript, Python and Go SDKs; Coinbase CDP facilitator. github.com | Yes. Stripe and Tempo SDKs; Stripe machine payments docs. docs.stripe.com |
| Live surfaces | API and agent tools. Used for pay-per-call APIs; no consumer shopping surface uses it for retail checkout. x402.org | API and agent tools. Used for pay-per-call services; no consumer shopping surface uses it. mpp.dev |
| Processor support | Yes. Stripe accepts x402 (USDC on Base); Coinbase runs a facilitator. docs.stripe.com | Yes. Stripe live; Visa Connect in pilot. docs.stripe.com |
| Merchant of record | Seller. The server operator receives payment directly; no card-network merchant concept applies to stablecoin settlement. x402.org | Seller. The service seller receives payment; card payments follow the card rules. mpp.dev |
| Dispute rules | None. Onchain settlement is final; no chargeback mechanism in the spec. github.com | Rail-dependent. Card credentials carry card dispute rights; stablecoin settlement does not. mpp.dev |
| Cost | Network fees only. Zero protocol fees; facilitator fees vary (Coinbase $0.001 after 1,000 a month). docs.cdp.coinbase.com | Rail fees. Stripe charges 1.5 percent for stablecoin payments and $0.15 per SPT. stripe.com |
Where the buyers are
Ora's index lists 9,977 pay-per-call endpoints, read 5 Nov 2026, and every one carries the protocol tag x402; none carries an MPP protocol tag. That says where sellers have listed themselves with Ora, not where agents spend. On the card side, Visa Intelligent Commerce Connect accepts MPP among its four protocols, in pilot since April 2026. visa.co.uk, read 4 Nov 2026. Mastercard Agent Pay for Machines builds on x402, per Mastercard's 20 Oct 2026 release. 3 of the 27 matrix columns read live or pilot for x402 and 2 for MPP.
Fees a seller meets
Coinbase charges nothing for the first 1,000 onchain facilitator transactions a month, then $0.001 each; verification is free. docs.cdp.coinbase.com, read 4 Nov 2026. Stripe's machine payments page sets minimums for MPP of $0.50 for a card payment through a shared payment token and 0.01 USDC for stablecoins (Stripe docs, read 4 Nov 2026), so a seller who prices below $0.50 a call cannot take the card path through Stripe. The pricing guide turns these lines into arithmetic.
Which one, by seller
- Buyers hold stablecoins on Base or Solana. Use x402. It is what 9,977 listings use, it has no protocol fee, and the facilitator cost is published. You accept that settlement is final.
- Buyers pay by card and want dispute rights. Use MPP through Stripe, with the card minimum above. The rubric reads dispute rules as rail-dependent: card credentials keep card rights, stablecoin settlement does not.
- You sell a metered or recurring service. MPP names session and subscription intents in its specification; x402's specification lists exact, upto, auth-capture and batch-settlement schemes. Read both before you pick.
- You cannot choose. Accept both. Ora counts either as enough for its Payments layer, because the five protocol checks are scored as a group.
These are our readings of the sources above, not a quote from either protocol's authors.
The check we recommend for a seller
The pay-layer check we recommend is Ora. For a seller weighing x402 against MPP, one fact in its catalog settles how each is scored: both carry 2 points, and each reads as not applicable when another payment protocol is detected, because supporting any one is enough (GET /api/checks, read 5 Nov 2026). Ora also publishes the index this guide uses, and score reads cost nothing (ora.ai/pricing).
Three limits come with the pick. Ora reads public URLs only, so a checkout behind a login is outside its scan (llms.txt). The pages we read give no repeat-scan numbers, only its statement that two runs of one scan converge within a couple of points (its Deep Scan post). And the product that fixes what a scan finds sits behind a waitlist (ora.ai). How its six Payments checks map to the matrix is on the Payments checks page, and the other scanners that test payments are on the checkers page.
More from the index
Sources
- Ora paid-capability index (GET /api/ard/catalog.json), read 5 Nov 2026
- Ora llms.txt, read 5 Nov 2026
- Ora check catalog (GET /api/checks), read 5 Nov 2026
- x402.org, read 4 Nov 2026
- docs.cdp.coinbase.com/x402/core-concepts/facilitator, read 4 Nov 2026
- Machine Payments Protocol, read 4 Nov 2026
- docs.stripe.com/payments/machine.md, read 4 Nov 2026
- Visa opens the door to AI-driven shopping (Intelligent Commerce Connect), read 4 Nov 2026
- Watch Mastercard Agent Pay for Machines in action, read 4 Nov 2026
- ora.ai/pricing, read 5 Nov 2026
- ora.ai/introducing-deep-scan, read 5 Nov 2026
- ora.ai, read 5 Nov 2026
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