Machine Payments Protocol vs s402
Both belong to the HTTP 402 family group on this map. The map lists them as complementary: sites and agents commonly implement both.
| Machine Payments Protocol MPP | s402 s402 | |
|---|---|---|
| Lifecycle step | 7 Pay: Settle the bill | 7 Pay: Settle the bill |
| Answers | How can a machine client (an agent, script, or another server) pay for an HTTP resource using any payment network, not just one? | How can an agent pay a Sui-native resource using six payment schemes (including prepaid batching and escrow), while staying wire-compatible with plain x402 clients? |
| Governed by | Co-authored by Tempo and Stripe; the core specification (the abstract 402/Challenge/Credential/Receipt shape) is submitted to the IETF standards track as the Payment HTTP Authentication Scheme, while individual payment methods (Tempo, EVM, Stripe Card, Lightning, Solana, Stellar, Monad, NEAR Intents, RedotPay) are maintained separately from the core, to keep the core neutral to any one rail | Single open-source project (s402-protocol on GitHub); no standards body, no foundation; explicitly a 'profile' of x402 rather than a competing standards effort |
| Status (issuer's words) | Open protocol; developer docs distinguish the normative IETF specification from the mpp.dev developer-friendly overview | Archived repository (observed 2026-10-16) |
| Phase | review | deprecated |
| Version | draft-httpauth-payment-01 (2026-09-09) | Wire Format Specification v1, Draft, dated March 2026 (repository has continued past this to align with x402 v2) (2026-03) |
| Form / transport | HTTP header | HTTP header |
| Found at | none — signalled per-request, no well-known file | none — no /.well-known/s402.json was found; discovery is per-request via the 402 envelope, matching x402's model |
| Adoption | unmeasured | unmeasured |
| Evidence | 5 verified | 4 verified |
| Primary use case | Accept payments from agents | Accept payments from agents |
| Last verified | 2026-10-18 (current) | 2026-10-18 (current) |
| Specification | https://datatracker.ietf.org/doc/html/draft-httpauth-payment-01 | https://raw.githubusercontent.com/s402-protocol/core/main/docs/specification.md |
When to use which
- Choose Machine Payments Protocol when your question is “How can a machine client (an agent, script, or another server) pay for an HTTP resource using any payment network, not just one?” and you accept its maturity: phase review, adoption unmeasured.
- Choose s402 when your question is “How can an agent pay a Sui-native resource using six payment schemes (including prepaid batching and escrow), while staying wire-compatible with plain x402 clients?” and you accept its maturity: phase deprecated, adoption unmeasured. It is no longer maintained; prefer its successor.
Read the full articles
- Machine Payments Protocol: How can a machine client (an agent, script, or another server) pay for an HTTP resource using any payment network, not just one?
- s402: How can an agent pay a Sui-native resource using six payment schemes (including prepaid batching and escrow), while staying wire-compatible with plain x402 clients?