RoslynPad: a cross-platform C# editor that compiles against your installed .NET SDK

What RoslynPad is for, and who reaches for it

RoslynPad is a C# editor, not an IDE. The README describes it as "a cross-platform C# editor powered by Roslyn and the Morgania editor - an Avalonia editor based on the vs-editor-api repo." That sentence is the whole design brief: take the Roslyn compiler platform, which already knows how to parse, bind and analyse C#, and put an editor in front of it that runs on more than one operating system.

The audience is anyone who wants to run a short C# program without creating a project. A LINQ query over a list, a regex you are trying to get right, a quick look at how a library API behaves. The repository topics list diagnostics, dotnet and editor alongside avalonia and cross-platform, which matches that framing: the value is the language service, not the project system.

It is also aimed at people who already have a .NET SDK. The README opens its Installing section with a warning in bold: "You must also install a supported .NET SDK to allow RoslynPad to compile programs." RoslynPad is an editor that drives an SDK you install separately. It does not ship its own compiler toolchain.

How Roslyn and the Morgania editor fit together

Two layers are visible from the README. The lower layer is Roslyn, Microsoft's C# compiler and language service platform. The upper layer is Morgania, described as "an Avalonia editor based on the vs-editor-api repo." Avalonia is the cross-platform UI toolkit, and vs-editor-api is the editor API that RoslynPad reuses rather than writing its own text buffer and view model.

That inheritance explains the feature list. Completion, signature help, quick info, diagnostics and code fixes are all language-service features that Roslyn produces and the editor surfaces. Each has a screenshot in the README. NuGet packages and document management are the two features that go beyond pure language services: RoslynPad can add package references and keep more than one document around.

Dump results is the feature that makes the scratchpad model concrete. A C# script that produces output has to put it somewhere, and the README's dump screenshot implies results are rendered rather than printed to a console that vanishes. The build side confirms the stack: the README lists `dotnet build`, Visual Studio Code with the C# extension, and Visual Studio 2026 (Windows only) as ways to build the source, and the repository root carries RoslynPad.slnx, Directory.Build.props, Directory.Packages.props and a global.json, the standard shape of a .NET solution that pins its SDK.

Installing RoslynPad and running a first script

The README gives four installation routes. On Windows, winget is the shortest:

winget install --id RoslynPad.RoslynPad

On macOS, Homebrew installs it as a cask:

brew install --cask roslynpad

The other two sources are the GitHub releases page and the Microsoft Store. The README does not describe a Linux package for any distribution, so check the releases page before assuming a Linux binary exists.

Whichever route you take, install a supported .NET SDK first. The README links to aka.ms/dotnet for that and states plainly that RoslynPad needs it to compile programs. If you skip this step, the editor will open but nothing you type will build.

Once it runs, the workflow is a document rather than a project. Create a new document, type C# at the top level, and let completion and diagnostics work as you go. If your snippet needs a library that is not in the default set, add it through the NuGet packages feature shown in the README. Then run the document and read the result in the dump view. There is no csproj to edit and no build configuration to choose, which is the point.

To build RoslynPad from source instead, the README gives three options: `dotnet build`, Visual Studio Code with the C# extension, or Visual Studio 2026 on Windows. The solution file is RoslynPad.slnx at the repository root.

Where RoslynPad stops being the right tool

RoslynPad is a scratchpad, and the README never claims otherwise. There is no mention of a debugger, breakpoints, a test runner, multi-project solutions, or build orchestration. If you need to step through code, run a test suite, or build a solution with several projects and their own dependency graphs, RoslynPad is the wrong instrument and the documentation does not pretend it can do those things.

The .NET SDK dependency is the second boundary. RoslynPad does not bundle a compiler, so on a locked-down machine where you cannot install an SDK, the editor is inert. That is a deliberate split, and it means RoslynPad's supported language version tracks whatever SDK you have rather than a version the app controls.

Platform coverage is the third. The README lists GitHub releases, the Microsoft Store, winget and Homebrew. Nothing in the README describes a Linux package. The project is cross-platform in its UI framework, but the documented distribution channels are Windows and macOS, so verify a Linux build exists before planning around one. Finally, the README does not document rollback or downgrade behaviour between releases, so if you pin a version, the upgrade path back is not described.

RoslynPad against LINQPad and NetPad

LINQPad is the comparison most people reach for, and it appears in the related searches for this project. The difference is the platform story. LINQPad is a Windows application; RoslynPad's UI is built on Avalonia and the README describes it as cross-platform, with Homebrew as a documented install route for macOS. If you are on macOS and want a C# scratchpad, that distinction decides the choice before any feature comparison starts.

NetPad is the other name that comes up. Both projects are C# scratchpads in the same family, and the documentation here does not give a feature-by-feature comparison, so the honest framing is that they occupy the same slot and you should evaluate them against your own workflow rather than on a claim from this page.

The editor layer is a third point of difference. RoslynPad uses Morgania, an Avalonia editor based on vs-editor-api. AvalonEdit, which also appears in the related searches, is the editor component associated with the SharpDevelop lineage and shows up in other .NET tooling. Choosing RoslynPad means choosing the vs-editor-api lineage for text editing, which is what makes the Roslyn language features line up cleanly. That is an architectural choice, not a feature checkbox.

Licence, releases and what an upgrade costs you

RoslynPad is MIT licensed, and the LICENSE file sits at the repository root. MIT is permissive: it allows use, modification and redistribution with the copyright notice and licence text retained. That matters if you want to embed RoslynPad's editor components rather than run the app, and the README points to a Packages document under docs/packages for the component story. This is a description of the licence, not legal advice; read the LICENSE file yourself if the terms affect a product you ship.

Release cadence is visible from the tags: 21.1 on 2026-06-07, 22 on 2026-07-20, and 22.1 on 2026-08-04. The last push to the repository was on 2026-09-19. Three releases in roughly two months is a steady rhythm, and the version numbers suggest minor releases rather than a fixed schedule.

The upgrade cost is low by construction. RoslynPad is a standalone editor with no project files to migrate, no database schema, and no server component. Upgrading means installing a new binary. The one thing to watch is the .NET SDK relationship: because RoslynPad delegates compilation to the SDK you installed, an SDK upgrade can change which language features your snippets accept independently of any RoslynPad release.

Editorial conclusion

RoslynPad suits developers who keep a .NET SDK installed and want a fast C# scratchpad with completion, diagnostics, code fixes and NuGet references without opening a solution. It is the wrong tool for anyone who needs a full project system, build orchestration or a debugger, and the README does not describe any of those. Verify two things before adopting it: that a supported .NET SDK is present on the machine, since the README states RoslynPad cannot compile without one, and that your platform has a binary in the releases page, since the README lists GitHub, winget and Homebrew as the only download sources.

Frequently asked questions

Official sources

1. License: MIT
2. Project website
3. README
4. Releases
5. roslynpad/roslynpad on GitHub