For Processing versions 2.0 and up, add contributed libraries by selecting "Add Library..." from the "Import Library..." submenu within the Sketch menu. Not all available libraries have been converted to show up in this menu. If a library isn't there, it will need to be installed manually by following the instructions below.

Prior to Processing 2.0, it was necessary to add libraries manually. Only follow the Manual Install instructions here if you are using an older version of the software or if the library you want to add isn't included in the "Add Library..." list mentioned above.

Contributed libraries may be downloaded separately and manually placed within the libraries folder of your Processing sketchbook. As a reminder, the sketchbook is where your sketches are saved. To find (and change) the Processing sketchbook location on your computer, open the Preferences window from the Processing application (PDE) and look for the "Sketchbook location" item at the top.

Copy the contributed library's folder into the libraries folder at this location. You will need to create the libraries folder if this is your first contributed library.

By default the following locations are used for your sketchbook folder. For Mac users the sketchbook folder is located inside ~/Documents/Processing. For Windows users the sketchbook folder is located inside folder Documents/Processing.

Let's say you downloaded a library with name theLibrary. Then the folder structure of this library inside the libraries folder should look like the one below. The top folder of a library must have the same name as the .jar file located inside a library's library folder (minus the .jar extension):

     Documents
           Processing
                 your sketch folders
                 libraries
                       theLibrary
                             examples
                             library
                                   theLibrary.jar
                             reference
                             src

Some folders like examples or src might be missing. After a library has been successfully installed, restart Processing application.

In some cases the top folder of a library does not exist after extracting from the downloaded zip file. In this case, the top folder must be created manually and given the same name as the .jar file inside folder library. After creating and renaming the top folder, move all extracted folders from the zip file in there.

For example, you downloaded the library otherLibrary, and the folder structure in the zip file looks like this:

     examples
     library
           otherLibrary.jar
           auxiliary.jar
     documentation
     src

You must create the otherLibrary folder in the libraries folder and copy the above folders inside, resulting in a structure like this:

     Documents
           Processing
                 your sketch folders
                 libraries
                       otherLibrary
                             examples
                             library
                                   otherLibrary.jar
                             documentation
                             src

After a library has been successfully installed, restart Processing application.

Another example: you want to use the Apache Common Collections library, which is a plain Java library (ie. not designed for use with Processing). The zip file contains a folder named commons-collections-3.2.1 with various files in it, including one: commons-collections-3.2.1.jar

You have to create the libraries/ApacheCommonCollections/library folder (the middle name can vary, but must have only letters and numbers) where you put the jar file renamed along the folder name (here, ApacheCommonCollections.jar, then).

Alternatively, if you need this library for only one sketch, you can just drag'n'drop the jar file on the PDE, it will put it in a folder named code in the sketch folder (you can also create the folder manually and put the jar file there yourself). This also works, of course, for regular Processing libraries. This solution isn't optimal if you plan to use the library in several sketches, as it will duplicate the library, taking up space and making difficult a possible upgrade.