F# Interactive Shell and Compiler
fsharp.exe is legitimate. It is the F# interactive shell and compiler shipped with the .NET/F# tooling, used to compile and run F# scripts and projects.
fsharp.exe is the executable for the F# tooling, acting as the interactive environment (fsi) and compiler for F# code. It enables you to write, execute, and test F# scripts and projects from command line or IDE integrations.
The executable provides compilation services by invoking F# compiler back-end, manages script execution, and supports interactive evaluation via F# Interactive, including type checking and error reporting.
Quick Fact: F# tooling uses fsharp.exe in tandem with fsi.exe for scripting and interactive sessions.
Yes, fsharp.exe is safe when it comes from official Microsoft/SDK distributions and not from untrusted sources.
The real fsharp.exe is NOT a virus. Malware can masquerade with similar names, so verify digital signatures.
C:\Program Files\Microsoft SDKs\FSharp\ or C:\Program Files (x86)\Microsoft SDKs\FSharp\. The executable should be C:\Program Files\Microsoft SDKs\FSharp\\fsharp.exe .C:\Program Files\Microsoft SDKs\FSharp\\fsharp.exe .C:\Program Files\Microsoft SDKs\FSharp\\fsharp.exe resource usage in Task Manager; excessively high CPU with no active build is suspicious.C:\Program Files\Microsoft Visual Studio\ or C:\Program Files\dotnet\. Unprompted background activity is suspicious.Red Flags: If fsharp.exe is located in unusual folders (like AppData, Temp, or System32), runs without user action, or lacks a valid signature, scan with antivirus and verify you installed the official F# tooling.
fsharp.exe runs when you compile or run F# code, or when IDE tooling invokes the compiler. It may also run during project builds or script executions.
Reasons it's running:
Yes, you can disable fsharp.exe usage by not building F# projects or by uninstalling the F# tooling. If you rely on F#, keep the tooling installed and disabled only for idle times.
If fsharp.exe is consuming unexpected resources:
Quick Fixes:
1. Close idle builds and IDE actions that spawn fsharp.exe
2. Restart IDE to clear temporary worker processes
3. Update F# tooling to latest
4. Increase memory limits for the IDE if supported
5. Check for malware masquerading as fsharp.exe (verify signature)
No, the legitimate fsharp.exe from Microsoft/SDKs is not a virus. Verify it's located under the official F# tooling directories like C:\Program Files\Microsoft SDKs\FSharp and has a valid signature.
Background analysis, code completion, or build tasks can keep it active. Check IDE processes and disable unnecessary features; ensure you are on supported tooling.
If you uninstall F# tooling or Visual Studio, fsharp.exe will be removed. Deleting it standalone can break builds that rely on F#.
Yes, you can disable F# tooling in IDE settings or stop builds. Blocking F# tooling entirely may affect F# development workflows.
F# tooling can launch during IDE startup for background analysis. Disable the related features or popups in the IDE settings or skip project loading.
Reduce open projects, disable heavy background features, update to latest tooling, and consider using incremental builds to limit loaded references.
Common locations include C:\Program Files\Microsoft SDKs\FSharp\<version> and similar SDK install paths; always verify the path comes from official tooling.