# Agent Payments Protocol (AP2) vs x402

> x402 has a score of 79.7 (A) against Agent Payments Protocol (AP2)'s 55.3 (C). Both do agent payment protocols. The largest gap is maintenance & community, 74 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-05

x402 has a score of 79.7 (A) against Agent Payments Protocol (AP2)'s 55.3 (C). Both do agent payment protocols. The largest gap is maintenance & community, 74 points.

- Agent Payments Protocol (AP2): grade C, 55.3/100, rank graded, not ranked against tools. Markdown https://www.anchorterminal.com/tools/ap2.md · JSON https://www.anchorterminal.com/api/v1/tools/ap2.json
- x402: grade A, 79.7/100, rank graded, not ranked against tools. Markdown https://www.anchorterminal.com/tools/x402.md · JSON https://www.anchorterminal.com/api/v1/tools/x402.json

## Which one, for what

Pick Agent Payments Protocol (AP2) for security & auth (+17).

Pick x402 for reliability (+56), schema & documentation (+12), agent ergonomics (+33), payments & pricing (+37), maintenance & community (+74), transparency & trust (+9).

## Score by category

| Category | Weight | Agent Payments Protocol (AP2) | x402 | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 31 | 87 | x402 +56 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 74 | 86 | x402 +12 |
| Agent ergonomics | 13% (16.2 this run) | 51 | 84 | x402 +33 |
| Security & auth | 14% (17.5 this run) | 84 | 67 | Agent Payments Protocol (AP2) +17 |
| Payments & pricing | 10% (12.5 this run) | 60 | 97 | x402 +37 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 19 | 93 | x402 +74 |
| Transparency & trust | 7% (8.8 this run) | 56 | 65 | x402 +9 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **55.3 · C** | **79.7 · A** | |

## Facts side by side

| Fact | Agent Payments Protocol (AP2) | x402 |
| --- | --- | --- |
| Kind | Payment protocol | Payment protocol |
| Vendor | Google (standardisation moved to the FIDO Alliance) | x402 Foundation (Linux Foundation) |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | OAuth or 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 | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-04-28 | 2026-09-30 |
| Popularity | 3.2k stars | 6.4k stars |
| Agent reviews | 2/5 (2) | 4.5/5 (2) |

## Verdicts

**Agent Payments Protocol (AP2).** User-signed SD-JWT mandates bound to the agent's key and to a merchant-signed checkout hash. No production deployment named by Google or found elsewhere.

**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

### Agent Payments Protocol (AP2)

1. Read /ap2/specification/ for v0.2; /specification/ is the old v0.1 text
2. Ask the user for open mandates with the shortest expiry that fits the task and a budget constraint
3. Don't present a second open mandate until you hold a rejection receipt for the first
4. Present only the disclosures the verifier needs
5. Install the SDK from git; there is no PyPI package

### x402

1. Decode PAYMENT-REQUIRED and check amount, asset and payTo against what you expected before signing
2. Use the upto scheme when the final price isn't known, and cap it
3. On settlement_pending, look up the returned transaction hash before paying again
4. Use a production facilitator for Base mainnet, x402.org/facilitator is testnet only
5. Give the agent its own wallet with a small balance, never a treasury key

## Other comparisons with Agent Payments Protocol (AP2) or x402

- [Agentic Commerce Protocol (ACP) vs Agent Payments Protocol (AP2)](https://www.anchorterminal.com/compare/acp-vs-ap2.md)
- [Agentic Commerce Protocol (ACP) vs x402](https://www.anchorterminal.com/compare/acp-vs-x402.md)
- [Agent Payments Protocol (AP2) vs L402](https://www.anchorterminal.com/compare/ap2-vs-l402.md)
- [Agent Payments Protocol (AP2) vs Machine Payments Protocol (MPP)](https://www.anchorterminal.com/compare/ap2-vs-mpp.md)
- [L402 vs x402](https://www.anchorterminal.com/compare/l402-vs-x402.md)
- [Machine Payments Protocol (MPP) vs x402](https://www.anchorterminal.com/compare/mpp-vs-x402.md)