Overview

Native HTTP payments with x402 protocol

x402 Payments

x402 is an open payment protocol that enables native HTTP payments using the 402 Payment Required status code. It allows any API or resource to accept cryptocurrency payments without integrating traditional payment rails.

For Buyers (Payers)

Authorize payments using MPC-managed wallets with threshold signing.

For Sellers (Facilitators)

Accept and settle x402 payments on-chain through Paratro’s Facilitator service.

Why x402?

• Pay-per-use APIs — Charge per request, per token, or per compute unit
• AI Agent Payments — Enable autonomous agents to pay for resources programmatically
• Micropayments — Settle fractions of a cent with on-chain efficiency
• No payment gateway — Direct wallet-to-wallet transfers using signed authorizations

What Paratro Provides

Paratro supports both sides of the x402 protocol:

Role	Capability	Description
Buyer	MPC TSS Signing	Generate EIP-712 payment authorizations via threshold signing — no private key exposure
Seller	Facilitator	Verify signed authorizations and execute on-chain settlement

Payment Schemes

Exact

Fixed amount — payer authorizes and settles an exact price. Supports ERC-3009 and Permit2.

Upto

Variable amount — payer authorizes a maximum, seller settles actual usage. Permit2 only.

How It Works

1. Buyer signs authorization

   The buyer creates a signed EIP-712 authorization via Paratro’s MPC engine, locking the USDC amount in their wallet.

2. Buyer sends signature to seller

   The signed authorization is sent as a payment credential (via HTTP header or API call).

3. Seller verifies signature

   The seller calls Paratro’s Facilitator /verify endpoint to validate the signature, amount, and time window.

4. Seller settles on-chain

   The seller calls /settle to execute the on-chain transfer. For upto scheme, the seller specifies the actual settlement amount.

Supported Networks & Tokens

Chain	Network	Token	Transfer Method
Ethereum	Mainnet / Sepolia	USDC	ERC-3009, Permit2
Base	Mainnet / Sepolia	USDC	ERC-3009, Permit2
Polygon	Mainnet / Amoy	USDC	ERC-3009, Permit2
Solana	Mainnet / Devnet	USDC	SPL Token Transfer

Coinbase Compatibility

Paratro’s Facilitator endpoints are fully compatible with the Coinbase x402 SDK (V1 and V2 payload formats). Any client built with @coinbase/x402 can use Paratro as its Facilitator without code changes.