OpenDevelop

OpenDevelop is an open-source Integrated Development Environment (IDE) for C# and the .NET platform, a modern continuation of the classic SharpDevelop code base. It is written almost entirely in C# and runs on .NET 10 via LibreWPF (the cross-platform, WPF-compatible runtime), on Windows, macOS, and Linux.

Screenshots

WPF designer for editing XAML with a live preview.

ILSpy integration: browse assemblies and decompile types side by side in an embedded pane.

Code coverage results with per-method markers in the editor.

Class diagram designer for visualizing type hierarchies.

Overview

The SharpDevelop project started in 2000, initiated by Mike Krüger. OpenDevelop keeps the original SharpDevelop v4/v5 architecture (the addin tree, the workbench, AvalonEdit, and the project system) while moving it forward:

• Cross-platform: WPF UI on .NET 10 through LibreWPF; builds and runs on Windows, macOS, and Linux.
• Modern project support: SDK-style .NET projects and the new .slnx solution format.
• ILSpy decompiler built in: navigate assemblies and decompiled source in a dedicated pane with assembly-list, language, and language-version pickers, all bound to the hosted ILSpy workspace.
• Semantic themes: full Light and Dark themes for the entire shell — window chrome, menus, toolbars, status bar, scrollbars, grids, and dialogs follow one coherent palette and switch at runtime.
• Extensible: the classic addin tree makes it easy to add pads, commands, and tools.

Features

• Code editor based on AvalonEdit with syntax highlighting, folding, bookmarks, and breakpoints.
• Solution explorer with per-node icons, overlays, and context actions.
• Debugger integration (breakpoints, locals, call stack) with SharpDbg.
• Class diagram generation and editing.
• WPF designer (XAML editing with preview).
• NuGet package management.
• Unit test support based on the Microsoft Testing Platform.
• Code coverage runner with editor markers with AltCover and coverlet.
• Start page with recent projects and quick open.

Building & Running

Requirements: .NET 10 SDK.

macOS

./launch.sh            # build OpenDevelop.Mvp.slnx and run
./launch.sh --no-build # run the last build output
./launch.sh --build-only
./rebuild-all.sh       # full rebuild of the app and its dependencies
./dist.macos.sh        # produce a distributable bundle

A DEVFLOW_DISABLE=1 environment variable turns off the built-in DevFlow automation agent (used by integration tests and interactive debugging through its HTTP API on localhost:9299).

Solutions

Solution	Purpose
OpenDevelop.Mvp.slnx	Main application solution

Tests

Unit and integration tests live in tests/. Integration tests drive the running IDE through the DevFlow agent's UI/automation endpoints (/api/v1/ui/*), which allows verifying real UI behavior (themes, menus, pads) deterministically.

Libraries

• AvalonEdit — code editor
• AvalonDock — docking framework
• SharpTreeView — tree views
• ILSpy — decompiler (hosted in-process)
• LibreWPF — WPF-compatible runtime for .NET 10
• NuGet — package management
• Microsoft Testing Platform — unit testing
• log4net — logging

License

MIT

Copyright

Copyright © 2002-2016 AlphaSierraPapa for the SharpDevelop team. Copyright © 2026 LeXtudio Inc.