IntelliJ IDEA compare tabs

One simple solution is the 'Compare with Clipboard' function (in your contextual menu - right click), which allows you to compare the contents of an editor tab with whatever is in your clipboard. As long as you can copy something, you can compare it against a file...

• Select two files (with pressed Ctrl) in project view panel → Right Mouse button → Compare Files.

• Right click on the file in project view → Compare With... (Ctrl+D)

• If you have opened one file in editor you can navigate in project view to another file and press right mouse button on that file Compare with Editor.

• It is possible to compare file against your clipboard content. View → Compare With clipboard

• Also you can use idea as external diff tool idea diff file1.txt file2.txt

Outdated; Old verison of IntelliJ: Also you can compare files from 'Commander' tab, just select two files in right and left panels, right click on any of them → Compare two files

There is a plugin Compare Tab With Editor which may not have existed when this question was asked. I'm using it with IntelliJ 2017.2.

There is an updated version for IDE versions 2020.3 — 2022.1, Compare Tab With Editor 2.

In 2019, select your file and "compare with editor" (which is your opened tab)

I use this to have a config file loaded in intelliJ (which is changed by the server, not stored in my project) and need to compare it to a baseline (in my project)