ZeroKit is a library of 50 free, client-side tools for freelancers, small businesses, and developers, covering everything from invoicing and rate calculators to Kanban boards and a regex tester. Everything runs entirely in your browser. No sign-up, no ads, no tracking, and no server ever sees your data. It's also fully open source. Built solo out of frustration with tools that hide basic functionality behind paywalls or sign-up forms for something that should just work instantly.