JAG3D (Java Applied Geodesy 3D) is one of the most popular open source least-squares software package for geodetic sciences. The Java-based application is distributed under the terms of the GNU General Public License (version 3). JAG3D is designed to combine hybrid terrestrial observations like leveling, directions, distances or vertical angles in a uniform and rigorous mathematical model. Moreover, GNSS baselines that are derived by Global Navigation Satellite System (GNSS) techniques are supported. More information about the least-squares software package JAG3D can be found at software.applied-geodesy.org.
JAG3D is written in the platform-independent programming language Java and, therefore, the software is runnable at each platform and operation system that provides a Java Runtime Environment and the JavaFX. JAG3D requires at least JRE version of Java SE 9.0, which can be found for several platforms at Oracles download page or at the OpenJDK-project pages.
JAG3D is a portable least-squares software package - no need to install or uninstall. Just download the lates version, unpack and run. The JAG3D manual is organized by a Wiki. Moreover, a support forum is available for technical support.