Core SDK Execution

The foundation layer for account-to-account operations

Core SDK Execution is the settlement engine that powers all Fast payments with two SDKs that handle the actual movement of funds — whether between Fast accounts or across external chains. The core SDK provides FastProvider for network queries and transaction submission, Signer for key management and signing, and TransactionBuilder for constructing operations. Both SDKs are pure and composable — no embedded configs, no environment variable reads.

fast-sdk

Package: @fastxyz/sdk Native operations on the Fast network. Use this for:

• Creating and managing Fast accounts with Ed25519 keys

• Sending payments between Fast accounts

• Querying account balances, nonces, and token metadata

• Signing transactions and messages

• Building complex operations (token creation, mint, burn, batch)

Key features:

• Sub-100ms settlement

• Zero gas fees

• Parallel transaction execution

Full API and code examples: fast-sdk README

allset-sdk

Package: @fastxyz/allset-sdk Cross-chain operations via AllSet (the "bridgeless bridge"). Use this for:

• Moving funds between Fast and EVM chains (Base, Arbitrum, Ethereum, etc.)

• Depositing USDC from external chains into Fast

• Withdrawing from Fast to external wallets

• Executing custom intents (swap, supply, any contract call) on destination chains

Key features:

• No wrapped tokens

• Pre-funded liquidity on destination chains

• No lock-and-mint risk

• Pure functions — no embedded configs

Full API and code examples: allset-sdk README