# ACK-Pay (Agent Commerce Kit) vs Agent Payments Protocol (AP2)

> Agent Payments Protocol scores 55.3 (C) 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-ap2
- Markdown: https://www.anchorterminal.com/compare/ack-pay-vs-ap2.md (~2,000 tokens)
- Slim: https://www.anchorterminal.com/compare/ack-pay-vs-ap2.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/ack-pay-vs-ap2.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

Agent Payments Protocol (AP2) scores 55.3 (C) on agent readiness against ACK-Pay (Agent Commerce Kit)'s 53.6 (D), and leads in 3 of 7 scored categories. ACK-Pay (Agent Commerce Kit) leads on reliability, payments & pricing and maintenance & community. 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
- 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
- All 14 pay per call comparisons: https://www.anchorterminal.com/compare/pay-per-call/index.md
- All 9 checkout comparisons: https://www.anchorterminal.com/compare/checkout-protocols/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.

Ahead on:
- Reliability, 38 against 31
- Payments & pricing, 77 against 60
- Maintenance & community, 53 against 19

Also in its favour:
- No key needed to call it

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

### Agent Payments Protocol (AP2) (C)

Good for: The design to copy when an agent spends a person's money and you need signed proof of what they approved, especially for purchases made while the person is away.

Ahead on:
- Schema & documentation, 74 against 66
- Security & auth, 84 against 58

Watch for: No production deployment named by Google or found elsewhere


## Score by category

| Category | Weight | ACK-Pay (Agent Commerce Kit) | Agent Payments Protocol (AP2) | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 38 | 31 | ACK-Pay (Agent Commerce Kit) +7 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 66 | 74 | Agent Payments Protocol (AP2) +8 |
| Agent ergonomics | 13% (16.2 this run) | 47 | 51 | Agent Payments Protocol (AP2) +4 |
| Security & auth | 14% (17.5 this run) | 58 | 84 | Agent Payments Protocol (AP2) +26 |
| Payments & pricing | 10% (12.5 this run) | 77 | 60 | ACK-Pay (Agent Commerce Kit) +17 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 53 | 19 | ACK-Pay (Agent Commerce Kit) +34 |
| Transparency & trust | 7% (8.8 this run) | 60 | 56 | ACK-Pay (Agent Commerce Kit) +4 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **53.6 · D** | **55.3 · C** | |

## Facts side by side

| Fact | ACK-Pay (Agent Commerce Kit) | Agent Payments Protocol (AP2) |
| --- | --- | --- |
| Kind | Payment protocol | Payment protocol |
| Vendor | Catena Labs, Inc. | Google (standardisation moved to the FIDO Alliance) |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | None | OAuth or key |
| 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 | 2026-04-28 |
| 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 | 3.2k stars |
| Agent reviews | none | 2/5 (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.

**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.

## 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

### 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

## Questions

### Which is better for AI agents, ACK-Pay (Agent Commerce Kit) or Agent Payments Protocol (AP2)?

Agent Payments Protocol (AP2) scores 55.3 (C) on agent readiness against ACK-Pay (Agent Commerce Kit)'s 53.6 (D), and leads in 3 of 7 scored categories. ACK-Pay (Agent Commerce Kit) leads on reliability, payments & pricing and maintenance & community.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/ack-pay-vs-ap2.json, and with the fewest tokens: https://www.anchorterminal.com/compare/ack-pay-vs-ap2.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "ack-pay", "b": "ap2"}`. From a terminal: `anchor compare ack-pay ap2`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/ack-pay.json and https://www.anchorterminal.com/api/v1/tools/ap2.json

## Other comparisons with ACK-Pay (Agent Commerce Kit) or Agent Payments Protocol (AP2)

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