# processing/processing Is Archived in Place: What the Old Processing 3 Source Tree Still Is > The repository processing/processing holds the Processing 3 Development Environment, its core and bundled libraries, and its README now redirects all development to processing/processing4. Here is what remains usable, what the layout tells you, and why the last release is still 3.5.4. **processing/processing** — ⚠️ Processing moved to processing/processing4 ⚠️ - Repository: https://github.com/processing/processing - Website: http://processing.org - Stars: 6,480 · Forks: 1,471 - Language: Java - License: NOASSERTION - Published: 2026-09-22 · Updated: 2026-09-22 · Language: en - Canonical page: https://hysenlabs.com/projects/processing-processing ## What processing/processing actually contains now The README opens with a warning callout: development has moved to processing/processing4. Everything below that warning is struck through, including the old bug-reporting instructions, the note about locked issues, and Ben Fry's January 2019 sign-off. That struck-through text is the clearest signal of the repository's state. It is not a README describing an active project with a migration note appended; it is a redirect with the previous contents left visible underneath. The top-level entries tell you what the tree holds: app/ for the Development Environment, core/ for the Processing core, java/ and build/ for the build plumbing, plus license.txt, CONTRIBUTING.md, ISSUE_TEMPLATE.md, todo.txt and done.txt. The README describes this as the official source for the Processing Development Environment (PDE), the core, and the libraries included with the download. So this is the Processing 3 line, not a general-purpose library and not a sketch gallery. The release list confirms where the line stopped. The three most recent releases are processing-0270-3.5.4 (2020-01-17), processing-0269-3.5.3 (2019-02-03) and processing-0268-3.5.2 (2019-01-23). The README states that since the 3.5.4 release in January 2020, development has continued in the new repository. The last push to this repository was on 2026-07-15, but nothing in the release history describes a new release after 3.5.4, so a recent push should not be read as a new version. ## Who the Processing 3 tree is still for The audience for this repository is narrow and specific. If you are writing a sketch, the download page at processing.org is the entry point the README points to, not this source tree. If you are building the PDE from source, the README sends you to the build instructions on the project wiki, and it asks contributors to follow the style guidelines when submitting code. That is the real audience: people who need to compile or modify the environment itself, or who need to read the core to understand how a sketch is executed. A second group has a legitimate reason to be here: anyone maintaining code that targets Processing 3 specifically. The core and the bundled libraries live in this tree, and the 3.5.4 release is the last one in it. If a library you depend on was written against Processing 3 APIs, the source you need to read is here, not in processing4. A third group should not be here at all. The README explicitly redirects bug reports and feature requests to the issue chooser on processing/processing4. Filing against this repository works against you, because the people who would fix it are watching the other one. The README also separates out Android Mode, the Video library and the Sound library into their own issue trackers, and notes that processing.js is not affiliated with the project. ## The layout of the PDE, core and bundled libraries The architecture visible from the repository is a split between the editor and the runtime. app/ is the Development Environment, the window you type sketches into. core/ is the Processing core that a sketch runs against. java/ and build/ sit underneath both as build infrastructure. The README frames the repository as three things at once: the PDE, the core, and the libraries included with the download. That three-part split matters when you are deciding what to check out; a change to the editor and a change to the core have different blast radii. The repository does not include the build files themselves, so the exact Gradle or Ant targets are not something this article can state. What the README does give is the pointer: build instructions live on the project wiki, and the style guidelines live there too. If you need to know how a sketch is compiled into a running window, the answer is in the source under core/ and app/, and the wiki is the documented route to building it. One practical consequence of the split: the bundled libraries are versioned with the release, not independently. The release tags follow a processing-NNNN-3.5.x pattern, which means the libraries and the core move together in this tree. If you need a library at a different version, the README's separate trackers for Android Mode, Video and Sound are where that conversation happens. ## Building Processing 3 from source: what the README gives you The README does not include build commands inline. It points to the build instructions on the project wiki, and the repository ships the pieces those instructions operate on. The honest tutorial here is therefore short, and it is about getting the tree and knowing where to look next. Clone the repository and confirm which line you are on: ```bash git clone https://github.com/processing/processing.git cd processing git log -1 --format=%H git tag --list 'processing-*' | tail -n 5 ``` The tag listing should show the processing-0268-3.5.2, processing-0269-3.5.3 and processing-0270-3.5.4 releases named in the release list. If you need the exact 3.5.4 state rather than the tip of master, check out that tag before building. From there, the README's instruction is to follow the build instructions on the wiki. The repository layout tells you what you will be compiling: ```bash ls app core java build ``` You should see the four directories named in the top-level listing. If app/ or core/ is missing, you cloned something other than this repository or checked out a partial state. The README's own example of contributing is to submit patches against this tree and follow the style guidelines, which is the workflow the wiki instructions assume. ## The failure mode: a recent push with a 2020 release The trap in this repository is the gap between activity signals and version signals. The last push was on 2026-07-15, which looks current. The newest release is processing-0270-3.5.4 from 2020-01-17, and the README says development continued elsewhere after that release. A push can be a README edit, a branch cleanup, or a redirect fix; it is not evidence of a new Processing 3 build. If you pick this tree expecting a patched 3.5.x line, the release list is the fact that should stop you. The second failure mode is reporting. The README's struck-through text still contains the old instruction to open issues here, and the visible warning above it says the opposite. A reader who skims to the struck-through section can file a bug in the wrong tracker. The README is explicit that bug reports and feature requests belong on processing/processing4, and that reference, website and examples issues go to processing-docs, with Android Mode, Video and Sound in their own repositories. The third is scope confusion. This repository is not the download. The README's own framing points at processing.org/download for the environment users run. Someone who clones this tree looking for a working sketch editor has taken the long route to something the download page provides directly. ## Processing 4 is the alternative, and the difference is the repository itself The alternative to processing/processing is processing/processing4, and the difference is not a feature list. It is that processing4 is where development, bug reports and feature requests now live, according to the README's warning. The README gives the reason for the split directly: the project moved to a new repository so that old files accumulated over the last 20 years could be cleaned out. That is a repository-history decision, not an API decision. So the practical comparison is about which tree you are reading. If you are debugging a sketch that runs on Processing 3, the core you want is here, and the 3.5.4 release is the last one in this line. If you are starting fresh, or filing anything, the README sends you to processing4. The one thing the repository history does not support is treating the two as interchangeable sources for the same code; the Processing 3 tree stops at 3.5.4 and the new repository is described as the continuation. For adjacent tooling, the README names separate homes: Android Mode, the Video library and the Sound library each have their own repositories, and processing.js is described as not affiliated with the project. If your question is about one of those, neither repository is the right tracker. ## Licence and the cost of staying on this tree The repository's licence identifier is NOASSERTION, and the tree ships a license.txt at the top level. That combination means the machine-readable licence field does not resolve to a standard identifier, so the file itself is what you have to read. This article cannot tell you what license.txt says, because its contents are not reproduced here. Before you redistribute anything from app/, core/ or the bundled libraries, open license.txt and read it; do not infer terms from the NOASSERTION label in either direction. The upgrade cost of staying here is a dead end rather than a migration. There is no newer Processing 3 release to move to: 3.5.4 is the last one listed, and the README states development continued in the new repository. Fixes you need will land in processing4, not here. If you patch this tree yourself, you own the patch, because the README directs pull requests and issues to the other repository. The maintenance cost of the redirect itself is near zero, which is the point. The repository exists so that links, tags and the Processing 3 source remain reachable. Reading it as a distribution you should track is the mistake. ## Conclusion Use processing/processing only if you need the Processing 3 source tree itself: the PDE, the core, or the libraries shipped with the 3.5.4 download. Anyone starting a new sketch, filing a bug, or requesting a feature should go to processing/processing4, because the README points bug reports and feature requests there and the newest release in this repository is processing-0270-3.5.4 from 2020-01-17. Before relying on it, verify three things: which branch or tag you actually checked out, whether the build instructions in the wiki still match the toolchain in the java/ and build/ directories, and whether the library you depend on has its own repository, since the README names separate trackers for Android Mode, Video and Sound. Treat this tree as the historical Processing 3 codebase, not as a maintained distribution. ## FAQ ### How do I install Processing from processing/processing? You do not install the environment from this repository. The README points at processing.org/download for the download, and this tree is the source for the PDE, the core and the bundled libraries. If you want to build it yourself, the README directs you to the build instructions on the project wiki. ### How do I install the Processing IDE from source? Clone this repository and follow the build instructions on the project wiki, which the README names as the place where the source build is documented. The README does not reproduce the build commands inline; it ships app/, core/, java/ and build/ for those instructions to operate on. ### How do I install Processing on Linux? The README does not describe a Linux-specific install path. It points to processing.org/download for the environment and to the project wiki for building the source, and the repository itself is the source tree rather than an installer. ### Where do I download Processing 3? The README points at processing.org/download for the environment. The last release in this repository is processing-0270-3.5.4 from 2020-01-17, and the README states development continued in processing/processing4 after that release. ### How do I use Processing? The README frames this repository as the source for the Processing Development Environment, the core, and the libraries included with the download, which is the environment you write sketches in. For actually using it, the README's pointer is the download page rather than this source tree. ### How do I download Processing? The README points to processing.org/download, which it names as the download page for the environment. This repository is the source tree behind that download, not the distribution itself. ## Sources - [Issues](https://github.com/processing/processing/issues) - [processing/processing on GitHub](https://github.com/processing/processing) - [Project website](http://processing.org) - [README](https://github.com/processing/processing/blob/master/README.md) - [Releases](https://github.com/processing/processing/releases) --- Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/processing-processing