Calculators in your browser: the best open-source math libraries and tools
From a simple sum to symbolic algebra, a lot can run entirely in your browser with no server involved. Here are the open-source libraries and calculators worth knowing — including the one that powers our own scientific calculator.
Why in-browser calculators are great#
A calculator written in JavaScript needs no server round-trip: it is instant, works offline, and your numbers never leave your device. Our Scientific Calculator works exactly this way.
The library we use: math.js#
math.js (Apache-2.0) is an extensive maths library for JavaScript and Node.js, created by Jos de Jong and first released around 2013. It handles real and complex numbers, units, matrices, big numbers and a flexible expression parser — exactly what you want behind a scientific calculator. We use its evaluate() function to turn what you type into a result.
Other client-side maths libraries worth knowing#
- decimal.js (MIT) — arbitrary-precision decimals, ideal for money where floating-point errors are unacceptable.
- bignumber.js / big.js (MIT) — lighter big-number libraries from the same author.
- Fraction.js (MIT) — exact fractions instead of decimals.
- expr-eval (MIT) — a tiny, safe expression parser when you don't need all of math.js.
- nerdamer (MIT) — symbolic algebra (simplify, differentiate, solve) in the browser.
Open-source calculator apps#
If you want a full application rather than a library:
- SpeedCrunch (GPL) — a fast, keyboard-driven scientific calculator.
- Qalculate! (GPL) — arguably the most powerful free desktop calculator, with units and symbolic maths.
- GNOME Calculator and KCalc (GPL) — the calculators shipped with the GNOME and KDE desktops.
- Numbat (and its predecessor Insect) — a unit-aware calculator that also runs right in your browser.
Try ours#
Prefer to just start calculating? Our Scientific Calculator and simple Calculator run entirely in your browser — free, private and instant.
Frequently asked questions
Which library powers your scientific calculator?
math.js, an Apache-2.0 licensed JavaScript maths library.
Do these calculators send my data anywhere?
No. Browser-based calculators compute locally; your numbers never leave your device.