Payment Layer
ACK-Pay is transport-agnostic, but every transport has compliance implications. This page maps the full payment lifecycle with compliance checkpoints at each stage.
Four Transport Protocols
ACK-Pay is the compliance abstraction layer. The actual payment flow depends on the transport protocol selected at discovery time. Each transport has different compliance characteristics, but all must satisfy the same regulatory requirements.
x402 embeds payment in HTTP headers (machine-native, fastest, no intermediary). ACP (Stripe) requires KYC-backed Stripe Link and defers compliance to Stripe's gateway. AP2 (Google) uses cryptographic mandates and pushes identity verification to the payer's device. ACK handles identity resolution before handing off to any payment transport.
Each transport reduces risk differently. x402 reduces intermediary risk at the cost of peer-to-peer trust. Stripe reduces technical risk at the cost of centralization. Google reduces friction at the cost of Google's PKI. ACK reduces identity spoofing risk by resolving the agent before any payment is attempted.
Interactive Demo
The eight-stage payment lifecycle from intent to finality, showing how ACK-ID resolves agent identity (Stages 1–2), the agent discovers an x402-gated resource (Stage 3), negotiates and transports payment (Stages 4–5), and settles on-chain (Stages 6–8).
Protocol Comparison
Four payment protocols compared across eight stages with compliance checkpoint annotations. Each protocol handles identity, discovery, transport, and settlement differently.
The x402 payment gate is live on Base Sepolia. Send a payment request, watch the 402 challenge-response, and see the settlement confirmation on-chain.
Try the x402 gate on Base Sepolia →| Protocol | Identity Layer | Settlement | Travel Rule Support | Audit Trail |
|---|---|---|---|---|
| x402 | ACK-ID (DID resolution) | Direct on-chain (Base, Ethereum) | Yes (metadata in HTTP header) | Cryptographic receipt |
| ACP (Stripe) | KYC via Stripe Link | Stripe settlement + on-chain bridge | Yes (Stripe Travel Rule compliance) | Stripe API + on-chain logs |
| AP2 (Google) | Google PKI + device attestation | Google Pay settlement + on-chain | Partial (requires additional mapping) | Google Pay API logs |
| ACK | ACK-ID (W3C DID + ZKP) | Transport-agnostic (deferred) | Yes (ACK-Pay metadata carries Travel Rule) | Cryptographic identity proof |