Swapper On-ramp

On-ramp from fiat or any supported EVM chain into Fast network — via CLI or AllSet SDK.

What the On-ramp Does

The on-ramp bridges funds from the outside world into Fast:

• Fiat → Crypto: Buy USDC with a credit card or bank transfer; USDC is then bridged to Fast as fastUSDC

• EVM → Fast: Deposit USDC from any supported EVM chain (Arbitrum, Base, Ethereum) directly into Fast via the AllSet bridge

Funds arrive on Fast as fastUSDC and are immediately usable for agent payments, x402 requests, or cross-chain workflows. No exchange account or CEX KYC is required for EVM deposits.

How to Use

CLI

The Fast CLI provides funding flows for both crypto deposits and fiat on-ramp entry points. In the current monorepo, fast fund crypto covers EVM-to-Fast deposits, while fast fund fiat returns a mainnet on-ramp URL for the selected Fast address.

The CLI wraps the underlying SDK flows where appropriate. For scripted integrations or custom orchestration, use the SDK directly.

SDK

Use @fastxyz/allset-sdk to execute deposits programmatically. The SDK provides createEvmWallet(), createEvmExecutor(), and executeDeposit() for bridging from EVM chains to Fast. All functions are pure — you pass all addresses and RPC URLs explicitly.

For complete API documentation and runnable code examples, see the AllSet SDK README on GitHub. See the AllSet SDK reference for an overview of how deposits, withdrawals, and intents work.

How AllSet SDK Enables the Bridge

The AllSet bridge is a two-step protocol built into @fastxyz/allset-sdk:

1. Approve + Deposit (EVM side): executeDeposit submits an ERC-20 approve (if needed) and a deposit transaction to the AllSet bridge contract on the source EVM chain

2. Mint on Fast (Fast side): The AllSet relayer observes the EVM event, cross-signs the proof, and mints fastUSDC to the receiver's Fast address

This means:

• No liquidity fragmentation — funds arrive as Fast-native USDC (fastUSDC)

• No waiting for finality — Fast settlement is sub-second once the EVM deposit confirms

• No user-controlled bridging keys — the relayer handles cross-chain proof generation

For advanced intent-based flows (custom calldata, deposit-back, revoke), see executeIntent() in the AllSet SDK reference.

Supported Tokens and Chains

EVM Source Chains

Chain	Chain ID	USDC Address	Status
Ethereum Sepolia	11155111	0x... (test USDC)	✅
Arbitrum Sepolia	421614	0x75faf114eafb1bdbe2f0316df893fd58ce46aa4d	✅
Arbitrum	42161	0xaf88d065e77c8cC2239327C5EDb3A432268e5831	✅
Base	8453	0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913	✅
Ethereum	1	0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48	✅

Fast Tokens (on Fast network)

Token	Description	Minted via AllSet?
fastUSDC	Fast-native USDC (1:1 USDC)	✅ (from EVM USDC)
testUSDC	Testnet equivalent	✅ (from test USDC)

Fiat On-ramp

Method	Region	Token Out	Status
Credit Card	US, EU, UK	USDC/testUSDC	Coming soon
Bank Transfer	US, EU	USDC/testUSDC	Coming soon

Fiat on-ramp is integrated via third-party providers. The current CLI exposes the entry point, while broader SDK wrappers and provider coverage continue to evolve. Track the high-level roadmap in the Funding Abstraction overview.

SDK Reference

SDK	Use for
@fastxyz/allset-sdk	EVM ↔ Fast deposits, withdrawals, intents
@fastxyz/sdk	Fast address conversion, transaction signing
@fastxyz/x402-client	Pay for x402 APIs with Fast or EVM funds