I built a small free tool for a very specific problem: knowing when a deer feeder will run empty. The Deer Feeder Corn Calculator takes a feeder's capacity and daily use and works out how long a fill lasts, so you can plan refills instead of finding an empty hopper. It runs entirely in the browser as a static web app, with a browser extension version too. No sign-up, no data collected, and it is free to use. Try it here: https://bestdeerfeeders.com/deer-feeder-corn-calculator/ — it comes from Best Deer Feeders, where I write deer feeder guides and comparisons.