Top Rated for RubyMine

TabNine

All-language autocompleter — TabNine uses machine learning to help you write code faster.

Validation-File Comparison

Plugin on GitHub | Cronn GmbH Website.

Grammar-Kit

BNF Grammars and JFlex lexers editor.

IDEA Jetty Runner

A plugin that allows you to quickly run Jetty from IntelliJ IDEA.

Non Project Files Unlocker

Disables annoying dialog for unlocking non-project files - IDEA-125379.

Save Actions

Supports configurable, Eclipse like, save actions, including "optimize imports", "reformat code", "rearrange code", "compile file" and some quick fixes for Java like...

Kubernetes

Support for editing Kubernetes resource files (versions 1.5 - 1.16).

Changelist Organizer

By 4ch1m
Automatically organizes your modified files by moving them into predefined changelists.

JLink

Right-click anywhere in the editor and click 'JLink' to create (and copy to clipboard) a sharable link directly to the desired location in the code.

Erlang

Erlang support for IntelliJ IDEA, RubyMine, WebStorm, etc.