Casper
Browser extension that automatically finds you better DeFi rates
Casper
Created At
Winner of
Uniswap Foundation - Best Uniswap API Integration 2nd place
Project Description
Casper is a browser extension that automatically finds you better swap and bridge rates. (Like Honey, but for DeFi)
Most DeFi users overpay on every trade and don't even know it. Comparing rates across dapps manually is painful, and even aggregators miss the best price sometimes. Casper runs quietly in your browser. When you're about to swap or bridge on any dapp, it detects the trade, checks Uniswap and Li.Fi for a better rate, and pops up if it finds one. You then simply execute the better trade in a couple clicks. That's it.
It works with your existing wallet — no setup, no new wallets. When there's nothing to save, you won't even know it's there.
We're starting with swaps and bridges, but the bigger vision is a DeFi assistant that monitors and improves every on-chain interaction you make.
How it's Made
Casper is a Chrome/Firefox browser extension built with a content script and background service worker. The core trick is generic intent detection. Instead of building custom integrations for every DEX, we intercept RPC calls and API requests at the browser level and use heuristic pattern matching to figure out what the user is trying to do (swap, bridge) and with what tokens/amounts. This works across most dapps without per-site configuration.
Once we detect an intent, we fetch competing quotes in parallel from the Uniswap API (leveraging Uniswap protocol routing and UniswapX) and Li.Fi (cross-chain aggregation across 60+ networks). If either returns a better rate than what the user is currently seeing, we render a popup overlay with the savings and an execution flow.
The heuristic engine pattern-matches against common DEX router function signatures and API response shapes to extract trade intent without needing ABIs or knowing which protocol the user is on. For edge cases, we built an extensible custom parser system so site-specific logic can be plugged in without touching the core engine. And since we operate at the request interception layer rather than the wallet layer, Casper works with whatever wallet the user already has installed without any integration.
