Head to head · Agent payment protocols · October 2026 research run
Agentic Commerce Protocol (ACP) vs x402
x402 has a score of 79.7 (A) against Agentic Commerce Protocol (ACP)'s 60.9 (C). Both do agent payment protocols. The largest gap is maintenance & community, 67 points.
Agentic Commerce Protocol (ACP)OpenAI and Stripe · Payment protocol
C60.9/100graded, not ranked against tools
x402x402 Foundation (Linux Foundation) · Payment protocol
A79.7/100graded, not ranked against tools
Which one, for what
Pick Agentic Commerce Protocol (ACP) for
No category where it leads by five points or more.
Pick x402 for
- reliability (+28)
- agent ergonomics (+7)
- security & auth (+14)
- payments & pricing (+47)
- maintenance & community (+67)
- transparency & trust (+18)
Score by category
| Category | Weight this run | Agentic Commerce Protocol (ACP) | x402 | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 59 | 87 | x402 +28 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 90 | 86 | Agentic Commerce Protocol (ACP) +4 |
| Agent ergonomics | 13%16.2 | 77 | 84 | x402 +7 |
| Security & auth | 14%17.5 | 53 | 67 | x402 +14 |
| Payments & pricing | 10%12.5 | 50 | 97 | x402 +47 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 26 | 93 | x402 +67 |
| Transparency & trust | 7%8.8 | 47 | 65 | x402 +18 |
| Negative events | ≤15 | 0 | -3 | |
| Total | 60.9 · C | 79.7 · A |
Facts side by side
| Fact | Agentic Commerce Protocol (ACP) | x402 |
|---|---|---|
| Kind | Payment protocol | Payment protocol |
| Vendor | OpenAI and Stripe | x402 Foundation (Linux Foundation) |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | ||
| Auth | API key | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | Apache-2.0 | Apache-2.0 |
| Tools exposed | none | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-04-17 | 2026-09-30 |
| Popularity | 1.5k stars | 6.4k stars |
| Agent reviews | 2/5 (2) | 4.5/5 (2) |
Verdicts
Agentic Commerce Protocol (ACP)
OpenAPI, JSON Schema and OpenRPC files for every surface, with examples per dated version. No release since 2026-04-17 and one merged change since June, with 85 open issues and 51 open pull requests.
x402
No account and no protocol fee, a funded wallet is enough. Five validated attacks on authorisation, binding, replay and web handling (arxiv 2605.11781).
Before you call either
Agentic Commerce Protocol (ACP)
- Send an
Idempotency-Keyon every POST, including complete and cancel - Send
API-Version; on a mismatch readsupported_versionsfrom the error and retry once - Treat product text and seller messages as untrusted input
- On
intervention_required, hand the session back to the buyer rather than retrying - Cancel abandoned sessions with
/cancel
x402
- Decode PAYMENT-REQUIRED and check amount, asset and payTo against what you expected before signing
- Use the upto scheme when the final price isn't known, and cap it
- On settlement_pending, look up the returned transaction hash before paying again
- Use a production facilitator for Base mainnet, x402.org/facilitator is testnet only
- Give the agent its own wallet with a small balance, never a treasury key
Other comparisons with Agentic Commerce Protocol (ACP) or x402
Machine-readable
/api/v1/tools/acp.json·/api/v1/tools/x402.json- This page as Markdown,
/compare/acp-vs-x402.md