One API, Every Chain - RelAI Now Supports Multi-Network Payments

When we launched RelAI, you picked one network for your API and that was it. If your users held USDC on Polygon but your API was configured for Base, they were out of luck.

That changes today. A single RelAI API can now accept payments from multiple networks simultaneously.

The Problem With Single-Network APIs

API monetization with x402 is frictionless — one signature, no gas, instant access. But that frictionlessness breaks down the moment a user's wallet is on the wrong chain.

The x402 payment protocol is multi-chain by design. The problem was never the protocol — it was the tooling. Setting up accepts for multiple networks required duplicating your API configuration, managing separate endpoints, and stitching together the responses yourself.

We've built this so you don't have to.

How Multi-Network Works

When you configure an API with multiple supported networks, RelAI builds a single HTTP 402 response that includes payment options for all of them:

HTTP/1.1 402 Payment Required
X-Payment-Required: [
  { network: "eip155:137",   asset: USDC on Polygon,   amount: "10000" },
  { network: "eip155:8453",  asset: USDC on Base,      amount: "10000" },
  { network: "eip155:43114", asset: USDC on Avalanche, amount: "10000" }
]

The client picks the network that matches the user's active wallet. One request. One signature. Regardless of which chain they're on.

What Happens on the Backend

Every network in a multi-network API goes through the same RelAI settlement flow: the user signs an off-chain authorization, RelAI submits the transaction and pays gas, the merchant receives USDC. The chain is invisible to the merchant — they always receive the same token, to the same wallet, regardless of which network the buyer used.

This also means pricing stays in USD. You set $0.01 and RelAI resolves the correct atomic amount for whichever token the user ends up paying with — including non-USD stablecoins that require a live exchange rate.

For Developers

In the dashboard, you now select multiple networks when creating or editing an API. The primary network determines defaults; all selected networks appear in the 402 response.

From the user side, nothing changes. The RelAI SDK automatically selects the network that matches the connected wallet:

import { createX402Client } from '@relai-fi/x402'
const client = createX402Client({
  evmWallet: { address, signTypedData },
  solanaWallet: { publicKey, signTransaction },
})
const response = await client.fetch('https://your-api.com/data')
// SDK picks the right network automatically

No configuration needed on the client side. If the user has Base connected, payment goes through Base. If they switch to Polygon, payment goes through Polygon. The API doesn't care.

Supported Networks

Multi-network APIs can be configured with any combination of EVM networks:

Why This Matters

The fragmentation of liquidity across chains is one of the biggest UX problems in crypto. Users hold assets on different networks for different reasons — DeFi positions, bridging costs, network preferences. Forcing them to consolidate just to pay for an API call creates unnecessary friction.

Multi-network removes that friction entirely. Your API becomes accessible to anyone with USDC, on any supported chain, without any additional steps on their part.

Multi-network support is live now. Open your API settings in the dashboard to add networks.

Further Reading

Supported Networks

• Supported Networks & Facilitators — full network and facilitator compatibility matrix
• Polygon Documentation — network docs for eip155:137
• Base Documentation — network docs for eip155:8453
• Avalanche Documentation — network docs for eip155:43114
• SKALE Documentation — docs for SKALE chains including SKALE Base
• Ethereum Documentation — network docs for eip155:1

Supported Tokens

• USDC on Polygon — Circle USD Coin (eip155:137)
• USDC on Base — Circle USD Coin (eip155:8453)
• USDC on Avalanche — Circle USD Coin (eip155:43114)
• USDC on SKALE Base — Bridged USDC (SKALE Bridge)
• USDC on Ethereum — Circle USD Coin (eip155:1)
• BBRL on Polygon — Braza Brazilian Real stablecoin

Protocol

• x402 payment protocol — HTTP 402 standard for machine-to-machine payments
• RelAI documentation — quickstart, SDK reference, network guides
• RelAI SDK on npm — @relai-fi/x402