# Core SDK Execution

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](https://github.com/fastxyz/fast-sdk/blob/main/packages/fast-sdk/README.md)

### 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](https://github.com/fastxyz/fast-sdk/blob/main/packages/allset-sdk/README.md)


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