# dotnet/project-system

The .NET Project System for Visual Studio

Repository: https://github.com/dotnet/project-system
Canonical: https://ross.abutalabs.com/products/project-system
Language: C#
License: MIT
License Family: permissive
Topics: visual-studio, cps, csproj, vbproj, csharp, visual-basic, fsharp, fsproj
Last push: 2026-08-24T16:45:26+00:00

## Health v2 (maintenance only)
Score: 67/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 99, release rhythm 8, longevity 100
- inputs: {"age_days": 3786, "days_push": 9, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1023, forks 416 (observed 2026-08-28T04:03:16.259750+00:00)

## What it is
The official .NET Project System for Visual Studio, built on the Common Project System (CPS) framework, which connects SDK-style C#, F#, and Visual Basic project files (.csproj/.fsproj/.vbproj) to IDE features such as Solution Explorer, designers, debugger, build, and language services. It replaces the legacy native COM-based project systems with a single managed, multi-threaded implementation that is extensible via MEF by Microsoft and third parties.

## Use cases
- manage SDK-style csproj and vbproj projects inside Visual Studio
- extend the Visual Studio project system with custom project properties or rules
- understand or debug how Visual Studio loads .NET project files
- add support for C#, F#, or Visual Basic projects in a Visual Studio extension
- customize project tree and build behavior for .NET projects in the IDE

## When to choose
- You are building a Visual Studio extension that interacts with SDK-style .NET projects
- You need to extend or customize how Visual Studio handles .csproj, .vbproj, or .fsproj files
- You want to contribute to or track fixes in the project system that ships with Visual Studio

## When to avoid
- You need a build engine or CLI for building .NET projects - use MSBuild or the dotnet CLI instead
- You work outside Visual Studio (VS Code, Rider, command line) since this is a Visual Studio-specific component
- You want Roslyn language services like IntelliSense or refactorings, which live in separate repositories

## Facets
- artifact type: plugin
- maturity: stable
- function: developer-tools, build-tool, editor
- domain: developer-tools, text-editors
- platform: windows, dotnet, editor-plugin
- tags: visual-studio, project-system, cps, msbuild, csproj, vbproj, fsproj, sdk-style-projects, csharp, visual-basic, fsharp, mef, ide, solution-explorer, desktop

## Member repositories
- dotnet/project-system (main) score 67

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:16.259750+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T07:08:37.420080+00:00, confidence not recorded.
  - readme: https://github.com/dotnet/project-system (fetched 2026-08-28T04:03:16.259750+00:00, sha dc1f8a69bfa4)
- Data as of 2026-08-30T08:39:29.467469+00:00.