Plugins and add-ons for GIMP

Gimp is one of the best programs you can find to replace the expensive and heavy program that is Adobe Photoshop. Although the battle over whether this can ever overcome the latter (or if they want it) continues to be debated endlessly, but so far GIMP users are more than satisfied with what their program can do.

Plugins

One of the best qualities in this program is the use of GIMP Plugins. Following the philosophy that developers like Firefox's started, this software gives the option to advanced users and developers to make extensions or plug-ins to improve its software, and to the users to use them without much complications.

By the moment, its installation is not as simple as Firefox extensions, but despite that, is simple enough for anybody to do it.

The Plug-ins are stored directly in a folder called "Plug-ins" folder in Gimp

Windows: the folder is located in C: \ Program Files \ GIMP-2.0 (or similar).
Mac: right-click and choose the application folder.
Linux: reveal the hidden folders in Home folder and look for. Gimp.

After copying the plug-ins (the complete files you download) in the corresponding folder is necessary to restart the program.

In GIMP Plugins Registry page you can find all plug-ins for GIMP. Although there are many other pages where you can find plug-ins categories and "top ten" lists:

For developers there are several resources to start doing your own plug-ins. GIMP uses libgimp Procedural API based on a database (PDB).

The PSPI plug-in

A plug-in that is indispensable for former users of Photoshop is the PSPI plug-in that lets GIMP to use Photoshop plug-ins. So one can increases the number of filters available to GIMP and Photoshop users don't need to sacrifice their library.

Script-Fu

This is a way to automate actions with scripting languages. The Script-Fu is a Scheme based extension language implemented using TinyScheme, GIMP can also be scripted in Perl, Python (Python-fu), or Tcl.

GAP

GAP plug-in is one of the most attractive plug-ins that can be found for the GIMP and already has many fans, developers and users support behind it. This is an advanced tool to create animations extending normal GIMPS capabilities. GAP is capable of saving animations in several formats including GIF and AVI. The animation function relies on the layering capability of GIMP.

GIMPShop

For those Adobe Photoshop newcomers that fail to adjust to the new layout, GIMPshop is a derivative of GIMP that re-arrange the user interface to mimic Adobe Photoshop. This is achieved by modifying menus and user interface items.