When After Effects starts, it loads plug-ins from the Plug-ins folder, which is in the Adobe After Effects CS4\Support Files (Windows) or Adobe After Effects CS4 (Mac OS) folder by default. Several plug-ins come with After Effects and are automatically installed in this folder. You can obtain other plug-ins for After Effects and other Adobe products from Adobe or other vendors. For specific instructions for installing a plug-in, see its documentation.

After Effects also loads plug-ins from a MediaCore folder, which is intended to hold plug-ins shared between After Effects and Premiere Pro. Some third-party plug-in installers install their plug-ins in this folder.

When loading plug-ins, After Effects ignores the contents of folders with names that begin and end in parentheses; for example, the contents of the folder (archived_effects) are not loaded.

When exchanging After Effects projects between computer systems, make sure that the plug-ins that the project depends on are installed on both systems. Similarly, if you are rendering a composition with multiple computers on a network, make sure that all plug-ins used in the composition are installed on all rendering computers.

On Mac OS, press Command+Option+Shift+Help to generate a list of all plug-ins loaded into After Effects (including version numbers). For information on using this command on Windows or with a Macintosh keyboard that doesn't have a Help button, see Todd Kopriva’s blog on the Adobe website.

After Effects comes with several third-party plug-ins, including Foundry Keylight, Synthetic Aperture Color Finesse, fnord ProEXR, and Cycore FX plug-ins. Some plug-in installers—including the installers for Keylight and Color Finesse—install documentation for the plug-ins in their subfolders in the Plug-ins folder.

Documentation for Cycore FX plug-ins is available on the Cycore website. For more information, see Effects overview and resources.

Documentation for fnord ProEXR plug-ins is available in a PDF document on the fnord website. For more information, see About 3D Channel effects.

Documentation for Color Finesse is available on the Synthetic Aperture website. For more information, see Color correction and adjustment.

Many plug-ins for After Effects are written in the C/C++ programming language using the After Effects SDK. Effect plug-ins written with C/C++ have the filename extension .aex. For information on developing plug-ins for After Effects with the C/C++ SDK, go to the After Effects Developer Center section of the Adobe website.

Kas Thomas provides a tutorial on the MacTech website that shows step by step how to write an After Effects plug-in.

Increasingly, many effect plug-ins for After Effects are written in the Adobe Pixel Bender language. Pixel Bender is designed to improve the performance of image-processing operations by taking advantage of multiple processor cores; multiprocessing for Pixel Bender effect plug-ins does not rely on the Render Multiple Frames Simultaneously option being selected.

Effect plug-ins written with Pixel Bender have the filename extension .pbk (for single-kernel effects) or .pbg (for multiple-kernel effects).

The Pixel Bender language is also used to write effects and filters for use with other Adobe software, including Flash and Photoshop.

For more information about Pixel Bender effect plug-ins and the Pixel Bender Toolkit, go to the Pixel Bender section of the Adobe website.

For information on plug-ins available for After Effects, go to the After Effects plug-in page on the Adobe website.

Other resources for purchasing and learning to use plug-ins for After Effects include the Toolfarm website and Lutz Albrecht’s plug-in guide on his Mylenium website.

To exchange plug-ins, scripts, projects, and other useful items with other After Effects users, go to the After Effects Exchange on the Adobe website.

For other sources of plug-ins, see After Effects community resources.