ecosystem: add Fast — payment infrastructure for agents and APIs

[xc93]

PR: Add Fast to x402 ecosystem

Title

ecosystem: add Fast — payment infrastructure for agents and APIs

Description

Adds Fast to the x402 ecosystem page.

What is Fast?

Fast is payment infrastructure for programmatic transactions. It enables agents, APIs, merchants, and services to request, authorize, send, and settle payments — fully programmatically, across both crypto and fiat rails.

Fast is built for scenarios where payment must occur before a task executes or a service responds: an API charging $0.01 per request, an agent paying another agent for compute, a workflow paying per inference step.

Three properties make this possible:

• Near-zero fees — micropayments work. An agent can pay $0.001 per API call without fees consuming the payment.
• Sub-second finality — payments settle in under one second with no pending states, no confirmation delays, no rollbacks.
• Mathematical verification — every transaction is provably correct. When infrastructure settles billions per day across millions of autonomous agents, correctness is a requirement.

x402 Integration

x402 is a first-class payment protocol adapter in the Fast SDK.

We maintain a complete x402 SDK at fastxyz/x402-sdk:

Package	Purpose
@fastxyz/x402-client	Pay for 402-protected content using Fast or EVM wallets
@fastxyz/x402-server	Protect API routes with x402 payment requirements
@fastxyz/x402-facilitator	Verify Fast certificates and settle EVM payments

Supported networks: fast-mainnet, base, arbitrum, ethereum

How Fast settles x402 payments

On EVM chains, the x402 flow separates signing (client) from settlement (facilitator pays gas). Fast collapses this into a single step: the client submits a transaction and receives a certificate — cryptographic proof of finality — in under one second. The facilitator verifies the certificate. No gas, no on-chain settlement step.

The client SDK also supports auto-bridge: agents holding USDC on Fast can transparently pay EVM-based x402 endpoints. The SDK bridges funds to the target chain before signing the EVM payment.

// Agent pays for a 402-protected API — one function call
const { body } = await x402Pay({
  url: 'https://api.example.com/premium',
  wallet: { type: 'fast', privateKey: '...', publicKey: '...', address: 'fast1...' },
});

Links

• Documentation: https://docs.fast.xyz/sdk-references/payment-protocol-adapters/x402-sdk
• SDK repo: https://github.com/fastxyz/x402-sdk
• Website: https://fast.xyz
• npm: @fastxyz/x402-client, @fastxyz/x402-server, @fastxyz/x402-facilitator

Checklist

• Working integration with x402
• Link to documentation and code examples
• Actively maintained
• Working mainnet integration

Files Changed

typescript/site/app/ecosystem/partners-data/fast/metadata.json  (new)
typescript/site/public/logos/fast.png                            (new)