Coverity Scan - Find and fix defects in your Java, C/C++ or C# open source project for free
Padlet - Visual boards for organizing anything.
SonarQube - SonarQube, a core component of the Sonar solution, is an open source, self-managed tool that systematically helps developers and organizations deliver Clean Code.
BookWidgets - BookWidgets is an excellent application that let you create engaging exercises in minutes and easily share a varied variety of beautiful and fun activities with your classroom and others.
Checkmarx - The industry’s most comprehensive AppSec platform, Checkmarx One is fast, accurate, and accelerates your business.
Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.