ReSharper is a productivity extension for Microsoft Visual Studio, developed by JetBrains and first released in 2004, that brings the kind of deep code intelligence pioneered in IntelliJ IDEA to the .NET ecosystem. Where Visual Studio at the time offered relatively limited code analysis, ReSharper added continuous, on-the-fly inspection of C#, VB.NET, and XAML, surfacing errors, warnings, and code smells as the developer typed and offering quick-fixes to resolve them.
JetBrains’ feature documentation organizes ReSharper’s capabilities into a few core areas. Code analysis and quality cover the on-the-fly inspections and automatic fixes. Refactoring and code transformation let developers apply solution-wide refactorings and smaller, safe code changes, along with code generation for boilerplate such as properties and overrides. Navigation and search provide fast traversal of a codebase, jumping to files, types, and members while tracking symbol usage, inheritance, and implementations across an entire solution.
These features made ReSharper one of the most widely adopted Visual Studio extensions among .NET developers. It also bundled a unit test runner, code templates, formatting tools, and specialized support for frameworks such as ASP.NET and ASP.NET MVC, effectively extending Visual Studio into a more analysis-driven environment that resembled JetBrains’ standalone IDEs.
ReSharper’s lineage is important to understanding JetBrains as a company. The same engine that analyzes C# inside Visual Studio also underpins Rider, JetBrains’ standalone cross-platform .NET IDE, which combines the ReSharper analysis backend with the IntelliJ Platform front end. In this way ReSharper sits at the intersection of JetBrains’ two major technology lines, its .NET analysis engine and its IntelliJ-based tooling.
In the broader history of developer tools, ReSharper demonstrated that a third-party vendor could meaningfully augment a major platform IDE rather than replace it. Many of the analysis and refactoring conveniences that .NET developers came to expect were popularized by ReSharper, and Microsoft itself later added comparable capabilities to Visual Studio and the open-source Roslyn compiler platform, narrowing the gap that ReSharper had originally exploited.