googlechromelabs/estimator.dev

EStimator is a tool that calculates how much smaller and faster a website could become if its developers switched from older JavaScript code to modern JavaScript syntax. You give it a URL, and it tells you the potential savings in file size and load time. The way it works is straightforward: it analyzes the JavaScript running on a given webpage and compares what's there against what would be possible using more up-to-date language features. JavaScript evolves over time, and older code often includes extra plumbing to support older browsers. Modern syntax is generally more compact, so converting can shave off bytes and help the page load faster. The tool crunches the numbers and shows you the estimated improvement. The service is stateless and does not store information about you or the URLs you analyze, though it does use a minimal Google Analytics ping to track page visits and the total calculated size difference. This would be useful for web developers, technical founders, or product managers who want to understand if updating their codebase is worth the effort. For example, if an e-commerce site is loading slowly, a developer could use this tool to check whether modernizing the JavaScript would meaningfully improve performance, before committing to the work. It helps quantify the upside in concrete numbers rather than guessing. It's worth noting that the project is no longer maintained. The team now recommends using the "legacy-javascript" audit in Lighthouse, which is a broader website performance tool, to get similar insights. The README doesn't go into detail on the internal implementation beyond noting it relies on Firebase for hosting and server functions.