Calculator apps: / Web

- Desmos - Online set of tools related to math, including a set of calculators, exams and more.

- Geogebra - Free online math tools for graphing, geometry, 3D, and more. Includes interactive graphical calculator.

Resources / Videos

]]>Calculator apps: / Mac

- Soulver 3 - Smart notepad with a built-in calculator.

Calculator apps: / Cross-Platform

- Parsify Desktop - Extendable calculator for the 21st Century.

Calculator apps: / Web

- Clcalc.net - Open-Source command-line style arbitrary precision calculator with mathematical, scientific, programming functions and more.

Calculator apps: / Cross-Platform

- Qalculate! - Cross-platform scientific calculator including unit/currency converters.

Calculator apps: / Android

- Scalar - Powerful math engine and math scripting language, that combines the simplicity of standard calculators with the flexibility of scripting.

Resources / Videos

]]>Calculator apps: / Windows

- Windows Calculator (⭐26k) - Simple yet powerful calculator that ships with Windows

Calculator apps: / Android

- Droid48 (src) (⭐67), Droid48 (app) - Android port of x48, the awesome HP48GX/SX emulator

Calculator apps: / Linux

- x48 (⭐28) - Emulate the HP48GX/SX, one of the best engineering calculators ever.

Calculator apps: / Cross-Platform

- J# Calculator Barebones - Very simple calculator written in J#. Made as program for J# newcomers to extend and learn from.

Calculator apps: / Web

- Calculator.net - Huge collection of various calculators.

Resources / Communities

- MathOverflow - Question & Answer site for professional mathematicians.

Calculator apps: / Android

- Wabbitemu - Emulate Texas Instruments graphing calculators on your device.

Calculator apps: / Cross-Platform

- calc (⭐457) - Simple, fast and intuitive command-line calculator written in Go.

Resources / Communities

- Calculators Subreddit - The place to share tips, tricks, and games regarding graphing or high powered calculators.

- Mathematics Stack Exchange - Great place to ask questions about math.

Resources / Tutorials

- Simple calculator app using React & Node.js - Really easy tutorial for beginners.

- Calculator in C++ using switch...case - How to create a basic calculator in C++ using switch...case.

- Simple calculator in Python - Create a simple calculator with Python.

Resources / Videos

]]>Calculator apps: / Cross-Platform

- mdlt (⭐146) - Command-line utility for quick math.

Calculator apps: / Android

- HiPER Scientific Calculator - Advanced scientific calculator, with lots of features, for example result history and themes.

- Calculator ++ - Scientific calculator with modern, Google Material Design interface.

- Google Calculator - Official calculator from Google.

- Samsung Calculator - New, official calculator from Samsung.

- Photomath (Camera Calculator) - Calculate math problems using camera.

- RealCalc - Scientific calculator with realistic interface.

Calculator apps: / Windows

- HiPER Scientific Calculator (Windows Edition) - Advanced scientific calculator with lots of features.

- in-line calculator (AutoHotkey Calculator) (⭐47) - Interface-less calculator for Windows that lets you do basic math without having to leave the line you're typing on.

- Old Windows 7/8 Calculator in Windows 10 - Opportunity to use old Windows 7/8 calculator in Windows 10.

- GraphCal - Professional calculator with unique features.

Calculator apps: / Mac

- Numi - Beautiful calculator with great features, including unit & time zone conversion.

- Calculator + ƒ - Powerful, extensible calculator for the Mac.

Calculator apps: / Linux

- Galculator (⭐106) - GTK 2 / GTK 3 based scientific calculator.

- KCalc (⭐25) - Calculator which offers many more mathematical functions than meet the eye on a first glance.

Calculator apps: / Cross-Platform

- Simple Electron Calculator (⭐4) - Basic, cross-platform calculator made with Electron.

- elcalc (⭐2) - Calculator with simple & beautiful interface.

- Material Design Calculator (⭐22) - Cross-platform material design calculator.

- SpeedCrunch - High-precision scientific calculator featuring a fast, keyboard-driven user interface.

- Liri Calculator - Cross-platform, Material Design calculator with all the features you would expect from a modern calculator.

Calculator apps: / Web

- Wolfram|Alpha - Computational knowledge engine.

- Web 2.0 Scientific Calculator - Online calculator, that provides basic and advanced mathematical functions useful for school or college.

- Calculator.js - Open-Source, web calculator with beautiful Google Material Design interface.

- Notepad Calculator - Calculator with user-friendly, unique notepad interface.