Wolfram Alpha

Wolfram Alpha is a "Computational Knowledge Engine" - different from a search engine, it answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that...

Freemium Android iPhone iPad Web Kindle Fire Windows Phone

Grapher

With Grapher, you can graph equations and data sets and visualize the results on your Mac in real time. Grapher displays algebraic relations, both implicit and explicit...

Free Mac OS X

NaSC

Its an app where you do maths like a normal person. It lets you type whatever you want and smartly figures out what is math and spits out an answer on the right pane.

Free Open Source Linux

Excalibur

Excalibur for Windows 32-bit version is a freeware full featured RPN-only calculator. This is a serious calculator for serious users. Excalibur takes up a small amount of resources for all it does so well.

Free Windows

Calculator++

A multipurpose calculator app with slick and intuitive user interface. Access additional features from the main screen of the app using gestures. It has a big variety of built-in functions and supports adding new user-defined functions.

Free Open Source Android Android Tablet

Precise Calculator

Programmable scientific calculator which has more than 150 mathematical functions and all of them return as many digits as you need. It can calculate with real numbers, complex numbers, fractions, vectors, matrices.

Free Open Source Windows

Arithmate Pro Calculator

A modern, scientific calculator that is easy to use. While other calculators display only one number at a time, this one shows you the whole expression you are inputting, leading to a much more user friendly experience.

Commercial Android

Omni Calculator

Omni Calculator is a web/mobile calculator that solves concrete problems such as mortgage payment, gross margin, body mass index, break-even point, etc.

Free Android iPhone iPad Web

GNU Units

The Units program converts quantities expressed in various scales to their equivalents in other scales. The units program can handle multiplicative scale changes as well as nonlinear conversions such as Fahrenheit to Celsius or wire gauge.

Free Open Source Linux

ESBCalc

ESBCalc is a Freeware Scientific Calculator for Windows with Infix Notation, Brackets, Scientific Functions (Trigonometric, Hyperbolic, Logarithmic - including Base 10, Base 2 & Natural - plus more), Memory, Paper Trail, Result History...

Freemium Windows

MyScript Calculator

With MyScript Calculator, perform mathematical operations naturally using your handwriting.

Free Android iPhone Android Tablet iPad

Insect

High precision scientific calculator with full support for physical units (web and terminal versions).

Free Open Source Mac OS X Windows Linux Web Self-Hosted

XCALC

XCALC is my little RPN calculator completely free to use, and still downloadable. XCALC is now a DEAD project. No work has been done on this project since 2012, and nothing more will be done either.

Free Open Source Windows Linux

Calculator Plus

Calculator Plus is a nice addition to hundreds of Calculator apps but with unique idea and innovative and user friendly designed buttons. A sound and smart person...

Free Android

Online Terminal Calculator

Online terminal based calculator, it is one of the most productive calculator in online, it uses terminal based approach instead of traditional push button based.

Free Web

Ruvenss Calculator

Simple yet very effective calculator with print capabilities and log registration.

Free Mac OS X Windows Linux Chrome OS

Unit Wolf

Unit Wolf is a unit conversion program created for quick and reliable conversions. Enter entire equations or just simple numbers. Convert between 170 currencies or...

Free Web

errProof

The website has a lot of useful and unique tools.

Free Web

Jim

Jim is a medical image display package that allows easy viewing and analysis of Magnetic Resonance, x-ray CT and other types of medical image. Jim is an up-to-the-minute design with a familiar user-interface.

Commercial Mac OS X Windows Linux Java Mobile