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Kalker (or "kalk") is a calculator program/website that supports user-defined variables, functions, differentiation, and integration. It runs on Windows, macOS, Linux, Android, and in web browsers (with WebAssembly). npm GitHub Build status

Kanban | Website - Try it out here!


  • Operators: +, -, *, /, !
  • Groups: (), [], ⌈ceil⌉, ⌊floor⌋
  • Vectors: (x, y, z, ...)
  • Matrices: [x, y, z; a, b, c; ...]
  • Pre-defined functions and constants
  • User-defined functions and variables. f(x, y) = xy, x = 5
  • Root finding using Newton's method (eg. x^2 = 64). Note: estimation and limited to one root
  • Derivative of functions (derivatives of noisy functions or of higher order can be a bit inaccurate). f'(2), sin'(-pi)
  • Integration. ∫(0, pi, sin(x) dx) or ∫(0, π, sin(x) dx), maybe sometimes be slightly off
  • Understands fairly ambiguous syntax. Eg. 2sin50 + 2xy
  • Syntax highlighting
  • Special-symbol completion on tab. Eg. write sqrt and press tab. It will be turned into
  • Sum function: sum(start, to, expression) Eg. sum(1, 3, 2n+1) is the same as 2*1+1 + 2*2+1 + 2*3+1 = 15
  • Piecewise functions: f(x) = { f(x + 1) if x <= 1; x otherwise }, pressing enter before typing the final } will make a new line without submitting
  • Load a file including predefined functions and constants. For example, if you're going to use kalker for physics, you load up your file with physics functions/constants when starting kalker. This is done either using the -i file flag or by putting files in a certain directory and then doing load filename inside kalker. More about files here
  • Different number bases: Either with a format like 0b1101, 0o5.3, 0xff or a format like 1101_2. The latter does not support letters, as they would be interpreted as variables
  • Misc: separate expressions by a semicolon to write them on the same line, use the ans variable to get the value of the previously calculated expression


Package managers


brew install kalker

Arch Linux

kalker in the AUR, eg. yay -S kalker


Kalker is available through nixpkgs. The most up to date version is also available as a flake.


Kalker is available from the official repositories, pkgin install kalker


Pre-compiled binaries for Linux, Windows, and macOS (64-bit) are available in the releases page.


Minimum rust version: v1.36.0. Make sure you have diffutils gcc make and m4 installed. If you use windows: follow the instructions here (don't forget to install mingw-w64-x86_64-rust in MSYS2).


Run cargo install kalker


  1. Go into the cli directory.
  2. Run cargo build --release
  3. Grab the binary from targets/release


Kalker is completely free and open source. If you wish to support further development of Kalker and contribute towards it one day getting published on the Google Play Store, you can do so here: PayPal


There are currently three different libraries related to kalker.

  • kalk: The Rust crate that powers it all.
  • @paddim8/kalk: JavaScript bindings for kalk. This lets you use it in the browser thanks to WebAssembly.
  • @paddim8/kalk-component: A web component that runs @paddim8/kalk, which let's you use kalk in the browser with a command line-like interface.


A more complete reference can be found on the website.


Defining: name(parameter1, parameter2, ...) = expression
Example: $ f(x) = 2x+3 $

Using: name(argument1, argument2)
Example: $ f(2) $


Defining: name = expression
Example: $ x = 3 $

Using: name
Example: $ x $


kalk and cli (Rust)

After making changes to the kalk library (in kalk/), you can easily try them out by going to the root of the project directory, and doing cargo run. This will start kalker (cli), with the new changes. If you're using Windows, you will need to follow the instructions here, but also make sure to install mingw-w64-x86_64-rust in MSYS2.

All Rust code is expected to be formatted with `rustfmt

web (Svelte, TypeScript, Sass)


  1. npm install
  2. npm run dev - this will automatically re-compile the project when changes are made

mobile (Android)


  1. npm install
  2. npm run build
  3. npx cap sync
  4. Build the project using Android Studio, or Gradle directly.