Applications (Desktop Software Reimplementations): open-source projects that exist because someone reverse engineered a closed product, sorted by GitHub stars.
Clean-room Photoshop-style photo editor written from scratch in pure Rust
Unofficial Bitwarden-compatible server written in Rust
A Flash Player emulator written in Rust
Open-source clean-room reimplementation of Microsoft Word in Rust
Winamp 2.9 reimplemented in HTML5/JS, including skin and playlist format support
Clean-room AutoCAD-style CAD and drafting application written in pure Rust
Open-source clean-room Excel-style spreadsheet in Rust
Patches the Notion desktop/Electron app to add themes and extensions
Open-source clean-room reimplementation of Microsoft PowerPoint in Rust
Open-source implementation of the uTools launcher and plugin platform
Clean-room reimplementation of Avid Pro Tools in pure Rust
Clean-room reimplementation of Figma in pure Rust: frames, auto layout, components, vector networks, prototypes
Unofficial Figma desktop client for Linux built around the web app
Unofficial Notion.so desktop app for Linux
Runs the Xunlei download package extracted from Synology on other Linux machines
Open source reimplementation of EA's SAGE RTS engine (C&C Generals)
Open-source reimplementation of Impulse Tracker
Obsidian reverse engineered to run as a self-hosted web app
Video and slide editor whose slide and design editors are ported from reconstructions of Claude's editors
Reverse engineered C port of the Software Automatic Mouth speech synthesizer
Open-source plugin-free reimplementation of Microsoft Silverlight on WebAssembly
Wolfram Language / Mathematica reimplementation in Rust
Runs Xunlei's Xware router download firmware as a Linux desktop download client
Open-source cross-platform replacement for Sony's Content Manager Assistant for PS Vita
Open-source TypeScript implementation of the SSTap game proxy client
Recompilation of Microsoft ReportViewer for .NET Core
Clean-room take on the Autodesk Revit BIM workflow in Rust
Open source reimplementation of Windows PowerShell for Mono
Reverse-engineered Adobe Shockwave player in Rust/WASM to run early-2000s web games
Open-source remake of the closed-source Memory Cleaner Windows utility without forced updates
Open-source browser rewrite of HyperCard and HyperTalk
Cross-platform desktop version of the Winamp 2.9 reimplementation
Restoring Picroma Plasma by reverse engineering its unknown instruction set
Community recreation of the TTPlayer (Qianqian Jingting) music player
Playable version of the Windows 9x 3D Maze screensaver built by reverse engineering
Java clone of Apple's HyperCard and the HyperTalk language
Rebuilt Windows Task Manager
Clean-room mail, calendar and contacts client in Rust for Microsoft 365 and Outlook.com
Repackages the Windows Notion Electron app to run natively on Linux
Clean-room reverse engineered VST 2.x interface headers
SGI ElectroPaint screensaver ported to Windows via decompilation
Linux implementation of the Figma local font helper service
Faithful 64-bit port of the SQ8L Ensoniq SQ-80 emulation plugin
Reimplementation of Adobe Lightroom in Rust with a Kotlin Android UI
macOS screen and camera recorder in Rust, modeled on a study of OBS Studio's architecture
Open-source SDK, decompiler and web player for Adobe Shockwave
Clean-room Rust reimplementation of the Paper design app
Reconstructed source code of geoWrite 2.1 for the Commodore 64
Patches and native Unix reimplementations of tools to use Symbian SDKs on Unix
Clean-room clone of the Fever RSS aggregator API
Reconstruction of the Intel 8080 toolchain including PLM80, ASM80, LINK80 and ISIS 4.1
Reverse engineering and re-implementation of Macromedia Shockwave
Reverse engineering of STRAY SHEEP The Screen Mate, a 16-bit Windows application
Clean-room reimplementation of Microsoft OneNote in Rust
Reimplementation of Wallpaper Engine for Linux
Clean-room reimplementation of FL Studio Mobile in Rust
Open-source reimplementation of Apple's Xcode command-line tools
Reimplementation of IBM Embedded ViaVoice / ETI Eloquence TTS in portable C
Independent RGBI dust-and-scratch repair for the Nikon LS-5000 scanner (Digital ICE replacement)
Clean-room reimplementation of Microsoft Outlook (classic) in pure Rust
The GlovePIE decompilation effort
Independent accounting app modeled on REA/Ghidra study of QuickBooks Desktop for Mac behavior
Decompilations of the Zune desktop ZuneShell.dll, UIX.dll and UIXControls.dll
Rust reconstruction of the Johnny Castaway screensaver engine (Windows 3.1)
Clone of the N64 SDK's mild.exe ROM linker
Clean-room project scheduling program in the style of Microsoft Project, in Rust
ActionScript 3 runtime for .NET
A reimplementation of the LISP-like 'Installer' scripting language.
Open-source clone of the WordStar word processor that edits WordStar files
Clean-room reimplementation of Adobe Acrobat in pure Rust
Readable C++ reconstruction of the WASM module behind Brazil's TSE electronic voting simulator
macOS app that opens and runs classic HyperCard stacks
Clean-room implementation of Adobe Flash/Animate in Rust
Open-source replacement for the N64 SDK makemask.exe
Microsoft Sam, Mike and Mary (SAPI 5) voices rebuilt in portable C, sample-accurate
Windows 10 Notepad reverse engineered and rebuilt in Rust
macOS and browser port of Gemtree's 2000 Desktop Games (Stress Reducers), rebuilt with REA and Ghidra
Import library for Aldus/Macromedia FreeHand documents
Reimplementation of Creative ALchemy and DirectMusic for old DirectSound games
Centigram TruVoice text-to-speech system rebuilt in portable C
ETI Eloquence 6.1 speech engine rebuilt in C with a drop-in ECI.DLL
Speech Plus Prose 2000 speech synthesizer decompiled and buildable as a library
Open-source replacement for the N64 SDK makerom tool
Linux host for the Virtual Desktop VR streamer, replacing its macOS capture and encoding
.NET 10 color picker for Windows built from an REA study of PowerToys' shipped binaries
Reverse-engineered reimplementation of the T.A.G. BBS software