Collatex seems to be the standard collation tool. Unfortunately I don’t much care for it. Also interestingly, the web site does not actually tell you how to run it locally! So here’s a quick note.
Collatext is a Java program, so you must have a Java Runtime Environment (JRE) installed, for version 8 or higher. I think Windows 10 comes with a JRE anyway, but I can’t tell because long ago I set up a Java development environment which overrides such things.
You download the .jar file for Collatex from here. Download it somewhere convenient, such as your home directory c:\users\Yourname.
Then hit the Start key, type cmd.exe, and open a command window. By default this will start in that same directory.
Then run the following command in the command window.
java -jar collatex/collatex-tools-1.8-SNAPSHOT.jar -S
This starts a web server, on port 7369, with error messages to that command window. (If you just want to start the server and close the window, do “start java …”).
You can then access the GUI interface in your browser on localhost:7369. This is the same interface as the “Demo” link on the Collatex website. You can load witnesses, and see the graphical results.
I think it’s best for collating a few sentences. It’s not very friendly for large quantities of text.