Cross-Chain Fee Comparator-and-Optimal-Route Selector

WHAT IT DOES

Cross-Chain Fee Comparator & Optimal Route Selector is a read-only DeFi tool that analyzes and compares the total cost of bridging tokens between EVM-compatible chains. It reads the current gas price on the source chain, the destination chain ID, and bridge contract addresses you provide. For each bridge, it evaluates the fee structure (fixed fee, percentage fee, and gas overhead), token addresses and decimals, current token prices from multiple sources, estimated gas costs for bridge operations, and recent bridge transfer times. The tool also checks bridge liquidity and availability, and reads your wallet balance. It then sorts all routes by total cost and presents the optimal route, including a detailed breakdown of all fees.

HOW TO USE

Connect your wallet via the built-in connector. Select the source network from the dropdown. Enter the source token address you wish to bridge. Choose the destination chain from the dropdown. Enter the destination token address. Specify the amount to transfer (in source token decimals). In the text area, enter the bridge contract addresses you want to compare—one per line. Click "compare routes." The tool will read on-chain data for each bridge and display: source chain, destination chain, source token, destination token, amount, current gas price on the source chain, and a sorted list of bridge routes showing total cost, fee breakdown, gas overhead, and transfer time. The optimal route is highlighted with a star and displayed in a dedicated section. All data is retrieved directly from the chain—no centralized APIs are used for the core fee calculation.

TECHNICAL MECHANISM

The tool uses ethers.js v5.7.2 to interact with the blockchain. For each bridge contract address, it queries the bridge's fee structure using view functions: `getFee(address token, uint256 amount)` for fixed and percentage fees, and `getGasOverhead()` for the gas overhead. Gas price is read via `provider.getGasPrice()`. Token decimals are fetched using the token contract's `decimals()` function. Token prices are obtained from multiple on-chain price oracles—the tool first attempts to read from Chainlink price feeds, then falls back to Uniswap V3 pool observations if the oracle is unavailable. For estimated gas costs, the tool simulates the bridge operation by calling `estimateGas` on the bridge's `transferTokens()` method. Bridge transfer times are estimated by querying recent `Transfer` events from the bridge contract, extracting timestamps, and calculating a moving average over the last 10 transfers. Bridge liquidity is checked by calling `getLiquidity(address token)` on the bridge contract. The tool also validates the user's wallet balance using `balanceOf(address)` on the token contract, ensuring the amount is spendable. All this data is aggregated per bridge, and the routes are sorted by total cost (sum of fixed fee, percentage fee, gas cost, and gas overhead). The lowest-cost route is marked as optimal.

WHAT IT CANNOT SEE

This tool cannot guarantee bridge fee accuracy during high volatility—fees may change between read time and execution. It cannot predict future gas price changes, which can significantly affect total cost. It cannot account for slippage in token swaps that may occur during bridging if the bridge uses a swap mechanism. It cannot detect bridge outages or temporary fee changes that occur after the comparison. It cannot verify bridge contract security—it does not audit the bridge's code. It cannot ensure that the quoted fees are final at execution time; bridges may apply different fees based on conditions. It cannot validate off-chain liquidity depth or ensure that the bridge has sufficient liquidity to process the transfer. It cannot detect bridge-specific promotions or discounts not reflected in the on-chain fee structure.

PLEASE NOTE

This tool is EVM-only and supports Ethereum, Polygon, BNB Chain, Arbitrum, Optimism, and Avalanche. All reads are performed through your connected wallet's provider—no central server or API key is used. The comparison is based on on-chain data at the time of query; actual fees may vary. Always double-check the optimal route before executing any transaction. Bridges listed are user-provided; the tool does not endorse any specific bridge. Use at your own risk.