Overview

The 1inch Cross-Chain Swap SDK (Fusion+) provides high-level functionality for performing atomic cross-chain swaps between EVM chains. Fusion+ enables swaps across different blockchains without bridges or messaging protocols.

Key Benefits

• No bridges needed — Atomic swaps via escrow contracts on both chains
• MEV Protection — Dutch auction mechanism prevents front-running and sandwich attacks
• Gas cost abstraction — Resolvers pay gas fees on both source and destination chains
• Native token support — Swap directly from ETH, AVAX, BNB, etc. without wrapping
• 13+ supported chains — Ethereum, Base, Arbitrum, Optimism, Polygon, BSC, Avalanche, and more

How Cross-Chain Fusion+ Works

1. Sign Order — The SDK generates a cross-chain order specifying source/destination tokens and chains
2. Dutch Auction — Resolvers compete to fill your order at the best price
3. Escrow Deployment — The winning resolver deploys escrow contracts on both chains
4. Secret Reveal — You reveal cryptographic secrets to unlock escrows and finalize the swap
5. Assets Delivered — Tokens arrive on the destination chain atomically

Core Methods

• getQuote — Fetches cross-chain pricing, including auction parameters and secret counts
• placeOrder — Signs and submits a cross-chain order for ERC-20 tokens (all-in-one)
• createOrder — Generates an order struct for native token swaps (requires separate submission)
• submitNativeOrder — Submits a native token order to the relayer
• getOrderStatus — Checks order status (pending, executed, expired, refunded)
• getReadyToAcceptSecretFills — Checks if escrows are deployed and ready for secret submission
• submitSecret — Reveals a secret to unlock escrows and finalize the swap
• WebSocketApi — Real-time order status updates as an alternative to polling

Integration Pattern

A typical ERC-20 cross-chain swap follows this flow:

1. Initialize SDK — Create an SDK instance with your API key and blockchain provider
2. Check Allowance — Ensure the source token is approved for the Aggregation Router
3. Fetch Quote — Get cross-chain pricing for your swap
4. Generate Secrets — Create cryptographic secrets for escrow locking
5. Place Order — Submit the signed order with hashlock and secret hashes
6. Monitor & Submit Secrets — Poll for escrow deployment, then reveal secrets to finalize

Interactive Code Example

Explore the complete implementation — this example demonstrates a cross-chain ERC-20 swap: