How x402 Settlement Works

AlgoVoi's x402 settlement enables AI agents and APIs to request and verify payments using the HTTP 402 Payment Required standard. It produces offline-verifiable receipts for transactions across supported blockchains. Here's how it works:

1. The HTTP 402 Challenge

When an AI agent or API client accesses a paid resource, the server responds with an HTTP 402 Payment Required status. This challenge includes: - A payment request specifying the amount, currency (e.g., USDC), and blockchain. - A payment pointer identifying the facilitator you run.

This step ensures the client knows payment is required before proceeding.

2. Client-Side Payment Signature

The client generates a payment signature using: - A private key (e.g., from AlgoVoi's Keystone SDK). - The payment request details (amount, blockchain, recipient). - A nonce to prevent replay attacks.

This signature proves the client's intent to pay and is sent back to the server.

3. Payment Response Header

The server forwards the client's signature to the facilitator you run (AV-RAILS), which: - Verifies the signature and compliance status. - Settles the payment onchain in USDC on supported chains. - Returns a payment response header to the server, confirming the transaction.

The server then grants access to the resource.

4. Onchain Settlement and Receipts

AlgoVoi handles the entire settlement process: - Onchain transaction: The payment is recorded on the specified blockchain. - Offline-verifiable receipt: A cryptographic receipt is issued, proving the payment for compliance and auditing.

Receipts can be independently verified using AlgoVoi's RFC 9421 Verifier SDK or the algovoi-reseal-verify tool.

5. Compliance and Interoperability

AV-RAILS, the self-hosted facilitator, supports: - Supported blockchains for onchain settlement. - Public API endpoints for: - Attestation: Verify payment receipts. - Screening: Check compliance status. - Agent Mesh: Enable agent-to-agent settlements with the same compliance guarantees.

Why Use AlgoVoi x402?

Seamless integration: Works with existing HTTP clients and APIs.
Multi-chain support: Settle payments on your preferred blockchain.
Verifiable receipts: Offline-proof for audits and regulatory reporting.

Get Started

For developers: Integrate the Keystone SDK or RFC 9421 Verifier SDK.
For businesses: get AV-RAILS, the self-hosted facilitator, via the Suite Store.
For compliance teams: Use the Evidence Auditor to verify batch signatures.

For more details, visit the AlgoVoi docs.