git squash 
Locally squash commits on a branch, without needing to resolve any conflicts
It works just like GitHub's "Squash and merge" or GitLab's "Squash commits".
Installation
With Homebrew on MacOS and Linux:
brew install sheerun/git-squash/git-squash
With curl on MacOS and Linux, including Windows Subsystem for Linux:
curl https://raw.githubusercontent.com/sheerun/git-squash/master/git-squash > /usr/local/bin/git-squash && chmod a+x /usr/local/bin/git-squash
Usage
# This tool requires that target branch is mergable to current one
# The easiest way to ensure it is to merge it and resolve any conflicts
git merge master
# Squash all changes on current branch that happened since master branch
git squash masterLicense
MIT