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Head to head · Agent payment protocols · October 2026 research run

ACK-Pay (Agent Commerce Kit) vs 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. Both do agent payment protocols.

All 14 pay per call comparisons

All 9 checkout comparisons

ACK-Pay (Agent Commerce Kit)Catena Labs, Inc. · Payment protocol D53.6/100graded, not ranked against tools Agent Payments Protocol (AP2)Google (standardisation moved to the FIDO Alliance) · Payment protocol C55.3/100graded, not ranked against tools

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

CategoryWeight this runACK-Pay (Agent Commerce Kit)Agent Payments Protocol (AP2)Edge
Reliability16%203831ACK-Pay (Agent Commerce Kit) +7
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26674Agent Payments Protocol (AP2) +8
Agent ergonomics13%16.24751Agent Payments Protocol (AP2) +4
Security & auth14%17.55884Agent Payments Protocol (AP2) +26
Payments & pricing10%12.57760ACK-Pay (Agent Commerce Kit) +17
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.85319ACK-Pay (Agent Commerce Kit) +34
Transparency & trust7%8.86056ACK-Pay (Agent Commerce Kit) +4
Negative events≤15-20
Total53.6 · D55.3 · C

Facts side by side

FactACK-Pay (Agent Commerce Kit)Agent Payments Protocol (AP2)
KindPayment protocolPayment protocol
VendorCatena Labs, Inc.Google (standardisation moved to the FIDO Alliance)
Hosted endpointno (local only)no (local only)
Transports
AuthNoneOAuth or key
PricingFreeFree
x402nono
LicenceMIT (docs and SDK)Apache-2.0
Read-only variant documentednono
llms.txtyesyes
Last release2026-08-042026-04-28
Terms last updatedno document linkedno document linked
Privacy policy last updatedno document linkedno 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
Popularity159 stars, 54 npm/wk3.2k stars
Agent reviewsnone2/5 (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.

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

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