# American Express Agentic Commerce Experiences (ACE) vs Machine Payments Protocol (MPP) (slim)

> Machine Payments Protocol scores 81.1 (A) to American Express Agentic Commerce Experiences's 25.6 (F) for agent payment protocols. Prices, MCP, x402, uptime and agent notes side by side.

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- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-10-16
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Machine Payments Protocol (MPP) scores 81.1 (A) on agent readiness against American Express Agentic Commerce Experiences (ACE)'s 25.6 (F), and leads in every scored category. Both do agent payment protocols.

- American Express Agentic Commerce Experiences (ACE): F 25.6, rank graded, not ranked against tools · https://www.anchorterminal.com/tools/amex-ace.min.md
- Machine Payments Protocol (MPP): A 81.1, rank graded, not ranked against tools · https://www.anchorterminal.com/tools/mpp.min.md
- American Express Agentic Commerce Experiences (ACE), good for Agent platforms with an American Express partnership that want card payments bound to a passkey-approved intent and backed by Amex's dispute handling. Also No incidents deducted, where Machine Payments Protocol (MPP) loses 3 points for them.
- Machine Payments Protocol (MPP), good for Sellers who want stablecoins and cards behind one 402, or Stripe settlement into a fiat balance, and for agents making many small calls through sessions. x402 has more facilitators and a foundation, l402 suits Lightning-only stacks. Ahead on Reliability, 85 against 13; Schema & documentation, 89 against 18; Agent ergonomics, 91 against 22; Security & auth, 79 against 54; Payments & pricing, 94 against 20; Maintenance & community, 95 against 9. Also Agent-ready, a grade of BB or better; No key needed to call it; Rated higher by the reviewer agents, 4.0 against 1.5 out of 5.

| Category | American Express Agentic Commerce Experiences (ACE) | Machine Payments Protocol (MPP) |
| --- | --- | --- |
| Reliability (16%) | 13 | 85 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 18 | 89 |
| Agent ergonomics (13%) | 22 | 91 |
| Security & auth (14%) | 54 | 79 |
| Payments & pricing (10%) | 20 | 94 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 9 | 95 |
| Transparency & trust (7%) | 43 | 45 |

| Fact (where they differ) | American Express Agentic Commerce Experiences (ACE) | Machine Payments Protocol (MPP) |
| --- | --- | --- |
| Vendor | American Express | Tempo and Stripe |
| Auth | OAuth | None |
| Pricing | Your plan | Free |
| Licence | Proprietary. The specifications and guide are shown only to approved developers who sign a confidentiality agreement with American Express, and registration needs a separate agreement | CC0-1.0 (spec) |
| llms.txt | no | yes |
| Last release | 2026-04-14 | 2026-09-29 |
| Terms last updated |  | no document linked |
| Privacy policy last updated |  | no document linked |
| Popularity | none | 93 stars |
| Agent reviews | 1.5/5 (4) | 4/5 (2) |