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x402 Payments — How AI Agents Pay for Scraping

· 3 min read
The Pry Team
The Pry Team
Pry Engineering

AI agents increasingly need to fetch web data: prices, listings, articles, compliance records. But agents can't fill out signup forms or click "confirm email". x402 solves this by making the HTTP status code 402 Payment Required machine-payable: the API asks for crypto, the agent pays from a wallet, and the call proceeds. No account, no API key — in the x402 lane, the payment is the credential.

The x402 protocol in one flow​

x402 (revived by Coinbase's x402 spec) works like this:

  1. The agent calls a paid endpoint with no payment.
  2. The server responds 402 Payment Required with a PAYMENT-REQUIRED header — a Base64-encoded JSON body containing the receiving wallet, amount, asset, and facilitator.
  3. The agent signs and broadcasts a payment (typically USDC) to that wallet.
  4. The agent submits the transaction to the server, which verifies it on-chain and returns an access token.
  5. The agent replays the token (X-Payment-Id header) until it expires.
curl https://api.pryscraper.com/v1/x402/pricing
# {"scrape": {"price_usd": 0.001}, "crawl": {"price_usd": 0.01}, ...}

Prices are per operation and published at /v1/x402/pricing, so an agent can budget before it spends: one page costs a tenth of a cent, a thousand-page bulk crawl costs ten cents.

EIP-3009: the settlement primitive​

On EVM chains, Pry verifies payments via EIP-3009 (transferWithAuthorization) — the USDC standard for gasless, signature-based transfers. The payer signs an authorization; the facilitator (or the server itself, via EIP-7702 self-verify) submits it on-chain. Permit2 and plain native transfers are also supported, so USDT, ARB, ETH, and WETH work alongside USDC.

Verification is real: the transaction is confirmed on-chain before an access token is issued, with a configurable TTL (PRY_X402_PAYMENT_TTL, default 3600s).

Multi-chain treasuries: EVM, Solana, Tron​

A Solana address can't receive an EVM transfer, so Pry keys receiving wallets by CAIP-2 network id — one treasury per chain family:

PRY_X402_ENABLED=true
PRY_X402_WALLET_BASE=0x...        # EVM treasury (shared across EVM chains)
PRY_X402_WALLET_SOLANA=...        # distinct base58 address
PRY_X402_WALLET_TRON=...          # distinct T-prefix address

Pry accepts payments across seven chains: Base, Ethereum, Arbitrum, Optimism, and Polygon (EVM, USDC/USDT and native assets), Solana (SPL: SOL/USDC/USDT), and TRON (TRC-20: USDT/TRX). EVM settlement is turnkey; Solana runs through an SPL/facilitator verifier; TRON is scaffolded for operators who enable it explicitly.

How agents auto-pay via MCP​

The friction point for agents is implementing the payment flow. Pry exposes 76 MCP tools, so an agent with an MCP client and a funded wallet can scrape without any bespoke payment code: the tool call returns the 402 challenge, the agent's wallet layer signs the EIP-3009 authorization, and the retry carries the payment. From the agent's perspective it's just another tool call that costs fractions of a cent.

This is the model we expect to win for machine-to-machine APIs: no onboarding funnel, no API-key provisioning, no minimum commitments — just a signed payment per call, settled on-chain.

Try it​

Commercial licensing and hosted plans: [email protected].