You should also take a look at https://diff2html.xyz/ and it's integration with https://diffy.org/ to share diffs with co-workers, also both Open Source. (Disclaimer: I created diff2html)
Codacy https://www.codacy.com can help teams reduce review time and improve the reviews quality. It also has insights for security and is free for Open Source. (Disclaimer: I work in Codacy)
Great to see that you are using diff2html (https://diff2html.xyz). I built it for Codacy trying to create a better diff experience when reviewing code. Also you can get PMD, Checkstyle as part of code reviews and pull requests @ Codacy.com and it is free for open source for ever.