Scilab

The most comprehensive tool to perform numerical calculations

Octave

Applied calculus software very similar to MATLAB

Gretl

Application for econometric analyses

Derive

Powerful tool for symbolic mathematic calculations

GeoEnZo

Digital board to teach and learn maths

Statgraphics

Carry out statistical analyses on your data

WinPlot

Generate 2D and 3D graphics

Mathematica

Platform for computational development

Graphing Calculator 3D

Draw any 2D or 3D function almost instantly

Microsoft Mathematics

Solve mathematical operations with this free tool

Mathcad

Software for engineering calculations

PASW

One of the most powerful statistic solutions on the market

Euler Mathematical Toolbox

Complete numerical and algebraic computation system

Geometry

Complete trigonometry and geometry calculations easily

Maple

Solve complex mathematical operations

MathType

Complete mathematical equation and formula editor

Messenger for Desktop

Facebook Messenger on your Windows desktop

Signal

Instant messaging and chat app that guarantees anonymity

Telefuel

Alternative Telegram client focused on productivity for PCs

WeChat

The Windows version of the popular Chinese messaging app

WhatSender

Send multiple WhatsApp messages from your PC

Windows Live Messenger

The departed Messenger by Microsoft

WhatsApp Viewer

Tool to view WhatsApp chats on PC

IMVU

Instant messaging and chats in 3D environments

Telegram Messenger

Telegram's desktop client for Windows

WA Web Plus

An extension to use WhatsApp Web with more functions

Facebook Messenger

Chat with your contacts from your desktop

LINE

Instant messaging from your PC

WhatsApp Messenger

The official version of WhatsApp for Windows

QQ International

The messaging application to communicate at global level

imo

Talk to your friends from your PC