PhpStorm

https://www.jetbrains.com/phpstorm/

Built in support for LESS.

Eclipse

Follow instructions here: http://www.normalesup.org/~simonet/soft/ow/eclipse-less.fr.html

When using this plugin, use @import without the url() notation.
This is still valid:

What is NDDT (NetBeans Drupal Development Tool)?

From its github site:

NDDT is a module for the NetBeans IDE that aides in the development of Drupal module and theme development. It provides rapid access to all the core Drupal hooks and theme override functions.

Basic Things the NetBeans IDE Drupal Plugin provides

Quickly Stub-Out Blank Module and Theme folders and files

To stub out blank module or theme folders and files under the "custom" folder:

1. Open the NetBeans Projects pane and right-click on the sites/all/modules/custom folder
2. Select New > Other > PHP > Drupal Module (or Drupal Theme)
3. Fill out the module name
4. Observe that the plugin will create a subfolder where specified, appropriately-named files, and open the files in NetBeans IDE editor for you

Drupal Code Completion

• Theme hooks
• Module hooks
• ...

Where to get the NetBeans IDE Plugins for Drupal

There exist both Drupal 6.x and 7.x plugins for NetBeans. At this time, only D6 plugin shows within the NetBeans plugin finder. To pick up the D7 NetBeans plugin, visit the plugin developer's git-hub project page: