LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
FreeCAD - An open-source parametric 3D modeler
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
SketchUp - 3D for Everyone
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.