5 Free Finance Calculators Every Developer Should Bookmark

Developers are great at solving complex problems — but personal finance often gets pushed to the backlog indefinitely. Between stock options, freelance rates, and the classic "maybe I'll retire early" dream, there's a lot of financial math that actually matters to us. I built a set of free, no-signup finance calculators using vanilla JavaScript. No frameworks, no accounts, no paywalls. Just open them and start calculating. Here are the five I think every developer should have bookmarked. 1. Compound Interest Calculator Compound Interest Calculator → This is the calculator Albert Einstein allegedly called "the eighth wonder of the world" (probably apocryphal, but still true). If you're putting money away in index funds, a HYSA, or anywhere that earns a return, compound interest is what makes it grow exponentially rather than linearly. As developers, we're used to thinking in algorithms — compound interest is literally P * (1 + r/n)^(nt) . Plug in your current savings, expected annual re