Cross-Chain Gas Comparator

WHAT IT DOES

Cross-Chain Gas Comparator is a powerful cost-optimization tool that helps you save money on transaction fees by comparing gas costs across multiple EVM chains in real-time. When you're about to execute any blockchain transaction—whether it's a wallet approval, token swap, NFT trade, or smart contract interaction—the tool automatically detects the transaction activity and displays a comprehensive gas comparison panel. It fetches current gas prices from Ethereum, Polygon, Arbitrum, Optimism, Base, Avalanche, and BNB Chain via public RPC endpoints, estimates the total transaction cost in native tokens and USD for each chain, and clearly identifies the cheapest execution option. The panel shows gas prices in Gwei, total cost in native tokens, and USD equivalent for each chain, with the cheapest chain highlighted with a star. When applicable, the tool also provides bridge cost estimates for moving funds between chains, helping you calculate the total cost including bridging. The quick-switch feature lets you open the same transaction on the recommended chain where supported by the dApp.

WHERE IT RUNS

This overlay operates on any website (matching all URLs) across the entire web. It works in any browser that supports the BotGentz extension framework and has an EVM-compatible wallet extension installed. The panel automatically activates whenever blockchain transaction activity is detected on the page.

HOW TO USE

Install the extension and connect your wallet. The tool automatically activates when you visit any page with blockchain transaction activity. The panel displays a comparison of gas costs across all configured chains, showing gas price in Gwei, total cost in native tokens, and USD equivalent for each chain. The cheapest chain is highlighted with a star. Configure your settings: select your preferred display currency (USD or native tokens), set the gas price update interval (10-120 seconds), configure a gas savings notification threshold, toggle bridge cost estimates, and manage which chains appear in the comparison using the chain selection dropdown. Use the "Refresh Gas Data" button to manually update prices, "Copy Comparison" to export the data, and "Reset Settings" to restore defaults.

MECHANISM: MULTI-CHAIN GAS PRICE AGGREGATION WITH REAL-TIME RPC QUERIES

The extension implements a parallel gas price aggregation system that queries multiple EVM chains simultaneously to provide accurate real-time comparisons. For each configured chain, the tool uses the eth_gasPrice JSON-RPC method via public RPC endpoints to fetch the current base fee, then applies a reasonable gas limit estimate (default 100,000 gas units) to calculate the total transaction cost. The gas limit can be adjusted based on the detected transaction type—approvals use lower limits, while complex swaps and trades use higher limits. The cost calculation converts the gas price (in Wei) multiplied by gas limit to native tokens, then uses the current token price (fetched from a price oracle or CoinGecko API) to display USD equivalents. The bridge cost estimation uses approximate fees from major bridge protocols (LayerZero, Axelar, etc.) to provide a total cost comparison that includes both transaction fees and bridge fees. The tool updates gas prices at the configured interval, caching results to minimize RPC calls and avoid rate-limiting. The quick-switch feature constructs a URL with the appropriate chain ID parameter for supported dApps that use multi-chain routing (e.g., Uniswap, 1inch, or OpenSea), allowing users to quickly switch to the cheapest chain for the same transaction.

THE PANEL

The overlay panel is fully draggable via its title bar and remembers its position per-site using GM_setValue. It snaps to the nearest edge when dragged within 40px of any screen boundary. The panel includes clear sections for gas comparison (domain, wallet address, current chain gas price, estimated gas limit), chain comparison (list of chains with gas price, cost in native tokens, USD cost, and cheapest indicator), bridge estimates (when enabled, shows bridge costs between the cheapest chain and others), settings (display currency selector, update interval selector, savings threshold input, bridge toggle), chain selection (dropdown to add chains, list of current chains), and action buttons (Refresh Gas Data, Copy Comparison, Reset Settings). The chain comparison section sorts chains by cost, with the cheapest at the top, color-coded savings percentages, and clear cost breakdowns. Pressing Escape temporarily dismisses the panel until you navigate to a new page or manually reactivate.

PLEASE NOTE

This extension requires the free BotGentz framework extension to be installed and active. You must also have a real EVM-compatible wallet extension (such as MetaMask, WalletConnect, Coinbase Wallet, or Rabby) already installed in your browser—the overlay uses your wallet's RPC provider for eth_call queries and transaction detection. This tool is read-only—it does not send transactions or modify gas settings; it only provides comparison data. The tool cannot estimate gas costs for transactions involving custom logic or complex contract interactions without accurate gas estimation; depends on RPC endpoints that may be rate-limited or unavailable; cannot predict gas price fluctuations that occur between comparison and transaction execution; does not support non-EVM chains where gas mechanics differ; cannot account for transaction submission priority fees or MEV costs; bridge cost estimates are approximate and may not reflect actual bridge fees; does not support chains that require different transaction formatting or gas calculation methods; and cannot guarantee that the recommended chain is compatible with the specific dApp or transaction type. No private keys, wallet balances, browsing history, or transaction data are ever collected, transmitted, or stored outside your local browser—all data is stored locally using GM_setValue. Gas prices are estimates only and may change before you execute the transaction—always verify the final gas cost in your wallet before confirming.