SimMerge 3.3 could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The most popular versions of the program 3.3 and 3.1. We recommend checking the downloaded files with any free antivirus. The common filename for the program's installer is simmerge.exe. This software is a product of EnSoft. The software lies within System Utilities, more precisely System Optimization.
From the developer:
SimMerge is the industry-standard Simulink diff/merge tool, and supports both two- and three-way merge for Simulink models. SimMerge’s three-way merge is the easiest and most reliable way to integrate changes from different team members into a single Simulink model.
You may want to check out more software, such as Registry Cleaner Optimizer or ClearPlay Easy Updates, which might be related to SimMerge.