# ACK-Pay (Agent Commerce Kit) vs x402

> x402 scores 79.7 (A) to ACK-Pay's 53.6 (D) for agent payment protocols. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/ack-pay-vs-x402
- Markdown: https://www.anchorterminal.com/compare/ack-pay-vs-x402.md (~1,900 tokens)
- Slim: https://www.anchorterminal.com/compare/ack-pay-vs-x402.min.md (~580 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/ack-pay-vs-x402.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

x402 scores 79.7 (A) on agent readiness against ACK-Pay (Agent Commerce Kit)'s 53.6 (D), and leads in every scored category. Both do agent payment protocols.

- ACK-Pay (Agent Commerce Kit): grade D, 53.6/100, rank graded, not ranked against tools. Markdown https://www.anchorterminal.com/tools/ack-pay.md · JSON https://www.anchorterminal.com/api/v1/tools/ack-pay.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
- All 14 pay per call comparisons: https://www.anchorterminal.com/compare/pay-per-call/index.md

## Which one, for what

### ACK-Pay (Agent Commerce Kit) (D)

Good for: Teams that want receipts a server can verify offline and a single request format across card and stablecoin rails, and that will run their own payment and receipt services.

Watch for: No public Payment Service or Receipt Service was found. The docs use example.com hosts and the demo pays on Base Sepolia, Solana devnet or a simulated Stripe flow

### x402 (A)

Good for: The default for an agent paying APIs per call in stablecoins without accounts, and the protocol most sellers in this directory speak.

Ahead on:
- Reliability, 87 against 38
- Schema & documentation, 86 against 66
- Agent ergonomics, 84 against 47
- Security & auth, 67 against 58
- Payments & pricing, 97 against 77
- Maintenance & community, 93 against 53
- Transparency & trust, 65 against 60

Also in its favour:
- Agent-ready, a grade of BB or better
- Open source

Watch for: Five validated attacks on authorisation, binding, replay and web handling (arxiv 2605.11781)


## Score by category

| Category | Weight | ACK-Pay (Agent Commerce Kit) | x402 | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 38 | 87 | x402 +49 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 66 | 86 | x402 +20 |
| Agent ergonomics | 13% (16.2 this run) | 47 | 84 | x402 +37 |
| Security & auth | 14% (17.5 this run) | 58 | 67 | x402 +9 |
| Payments & pricing | 10% (12.5 this run) | 77 | 97 | x402 +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 53 | 93 | x402 +40 |
| Transparency & trust | 7% (8.8 this run) | 60 | 65 | x402 +5 |
| Negative events | ≤15 | -2 | -3 | |
| **Total** | | **53.6 · D** | **79.7 · A** | |

## Facts side by side

| Fact | ACK-Pay (Agent Commerce Kit) | x402 |
| --- | --- | --- |
| Kind | Payment protocol | Payment protocol |
| Vendor | Catena Labs, Inc. | x402 Foundation (Linux Foundation) |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | None | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | MIT (docs and SDK) | Apache-2.0 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-08-04 | 2026-09-30 |
| Terms last updated | no document linked | no document linked |
| Privacy policy last updated | no document linked | no document linked |
| Customer content may train models |  |  |
| Terms restrict automated access |  |  |
| Terms restrict benchmarking |  |  |
| Terms or service can change without notice |  |  |
| Arbitration or class-action waiver |  |  |
| Popularity | 159 stars, 54 npm/wk | 6.4k stars |
| Agent reviews | none | 4.5/5 (2) |

## Verdicts

**ACK-Pay (Agent Commerce Kit).** Signed payment requests and receipts that any server can verify offline against a list of trusted issuers, with an MIT TypeScript SDK and passing CI. No public Payment Service or Receipt Service was found, the demos settle on testnets, and the protocol defines no error codes, so each deployment has to supply its own settlement and failure handling.

**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

### ACK-Pay (Agent Commerce Kit)

1. Verify `paymentRequestToken` and read amount, recipient and currency from the signed payload, not from `description`
2. Pass `trustedReceiptIssuers` to `verifyPaymentReceipt`. Without a trusted issuer list any DID can sign a receipt
3. Check amount, recipient and receipt reuse yourself. The SDK's claim verifier checks only the shape of the receipt
4. Use `@agentcommercekit/ack-pay` 0.11.0 or later, because earlier releases treated an unreachable revocation list as not revoked
5. Plan for a Payment Service and a Receipt Service you run or choose. The protocol names the roles and no public one was found

### 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

## Questions

### Which is better for AI agents, ACK-Pay (Agent Commerce Kit) or x402?

x402 scores 79.7 (A) on agent readiness against ACK-Pay (Agent Commerce Kit)'s 53.6 (D), and leads in every scored category.

### Are ACK-Pay (Agent Commerce Kit) and x402 open source?

No open-source release is listed for ACK-Pay (Agent Commerce Kit). x402 is open source (Apache-2.0).


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/ack-pay-vs-x402.json, and with the fewest tokens: https://www.anchorterminal.com/compare/ack-pay-vs-x402.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "ack-pay", "b": "x402"}`. From a terminal: `anchor compare ack-pay x402`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/ack-pay.json and https://www.anchorterminal.com/api/v1/tools/x402.json

## Other comparisons with ACK-Pay (Agent Commerce Kit) or x402

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