What is the PDE file format?
A .pde file contains the source code of an application written in the Processing programming language. .pde files are saved by default in a dedicated folder along with other files used by the application - for example, image assets. That folder must share the exact same name as the sketch; the Processing Development Environment concatenates all .pde files in the folder and compiles them as one program. The two core functions in any sketch are setup(), which runs once on startup, and draw(), which loops continuously to handle animation and interaction.
Released in 2001 by Ben Fry and Casey Reas at the MIT Media Lab, Processing was designed with the purpose of teaching fundamentals of computer programming to people with no prior programming background. It is implemented in Java and uses a simplified Java-like syntax. Processing is known for its visual presentation of code and processes, making it an ideal tool for visual art, generative design, and data visualization. It is distributed under an open-source licence and is maintained today by the Processing Foundation.
Early Arduino IDE versions also used the .pde extension for sketches before switching to .ino in Arduino IDE 1.0 (2011).
Security & safety
RISK: LOWA .pde is plain-text source code - it doesn't run by itself and is safe to read in any editor. The realistic caution is the same as for any downloaded code: a Processing sketch is full Java and can access the file system, network and external libraries, so read it before pressing Run if it comes from an untrusted source. The file itself carries no auto-executing payload; risk only arises when you choose to compile and run it.
Format details
in a nutshell- PowerDesk encrypted file - Some legacy databases list .pde for an encrypted file created by the PowerDesk file manager; niche/historical, unrelated to Processing.
- Pro/DESKTOP / CAD design files - A few older CAD/design tools used .pde for project/design data.
Programs that open PDE files
Windows3 apps
Processing
Open-source File > Open the .pde (it must be in a same-named folder), then press Run (the play button) to compile and launch the sketch's display window. 
Visual Studio Code (+ Processing extension)
Open-source Open the sketch folder; a Processing extension lets you run sketches via processing-java with richer editing than the PDE.
Notepad++ (read/edit only)
Open-source Open the .pde to read or edit the source without running it - handy to inspect code quickly. 
macOS1 app
Linux1 app
Processing
Open-source Open in the PDE and Run, or compile/run headless from the terminal with processing-java.
OpenProcessing
Freemium Browse and run Processing sketches in the browser (p5.js-based); good for viewing/sharing sketches without installing Processing. Technical details
deep spec| File category | Plain-text Java-based source code (Processing sketch) |
| Character encoding | UTF-8 |
| MIME type | text/x-processing (also accepted as text/plain) |
| Compression | None - uncompressed plain text |
| Sketch folder rule | The main .pde file must reside in a folder of the same name (e.g., mySketch.pde inside a mySketch/ folder) |
| Multi-file compilation | All .pde files in the sketch folder are concatenated by the PDE and compiled as a single program |
| Core API pattern | setup() runs once on launch for initialization; draw() loops continuously for animation and interaction |
| Host language / runtime | Processed to Java source and compiled with javac; runs on the Java Virtual Machine (JVM) |
| Supported platforms | Windows, macOS, Linux |
| File signature (magic bytes) | None - plain text; identified by content patterns such as setup(), draw(), and Processing API calls |
| Typical file size | A few hundred bytes to tens of KB (source code only) |
| Language mode variants | Java mode (default), Python mode (Processing.py), JavaScript mode (p5.js is the JS port) |
| Related Arduino extension | .ino - Arduino sketches formerly used .pde before Arduino IDE 1.0 (2011) introduced the .ino extension |
| Developer / maintainer | Processing Foundation; created by Ben Fry and Casey Reas, originally at the MIT Media Lab (2001) |
| Primary use cases | Visual art, generative design, data visualization, interactive media, programming education |
| Released | 2001 (Processing, MIT Media Lab); .pde is the Processing Development Environment sketch extension |
| Latest version | Processing 4.x (current as of 2024-2026) |
| Open standard | Yes · royalty-free |
| Specification | processing.org |
PDE conversions
Community Q&A
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