Source code file written in the Processing programming language; may contain functions, variables, and other programming constructs; used for storing Processing programs, called "sketches," and running them within the Processing IDE; can be used for programming images, animations, and interactions.

Each PDE file is stored in its own folder when saved from the Processing IDE. It is saved with any other program assets, such as images. The project folder and PDE filename prefix have the same name. When the PDE file is run, it is opened in a Java display window, which renders and runs the resulting program. Processing is commonly used in educational settings for teaching basic programming skills in a visual environment.

File used by ProntoDoc for Excel (PDE), a Microsoft Excel plug-in used for authoring and auto-filling document templates; saves a document template and includes the page layout structure as well as template fields that are filled by data from one or more source databases (SQL Server, SharePoint, and Oracle are supported); used for generating .XLSX, .PDF, and .XPS documents using data from small to enterprise-level databases.

ProntoDoc for Excel, a companion product of ProntoDoc for Word(PDW), is used in business environments for generating reports and other business documents.