Windows
Compatible applications
Quick Facts
Basic information about this file format
Extension
.FSX
File Type
F# Script File
Category
Programming
Best first step
Use compatible software
Quick Summary
A practical overview of the .fsx file format
An FSX file is a source code script written in F# (pronounced F sharp), which is a functional-first, multi-paradigm programming language that is part of the .NET ecosystem. Unlike standard .NET source files (like .fs) that are typically compiled into assemblies such as DLLs or EXEs before execution…
File extension
.FSX
File type
F# Script File
Category
Programming
Recommended action
Open with a trusted compatible app
How to open a .fsx file
Start with a trusted app that supports this format
- Check the file extension carefully and confirm that the file name really ends with .fsx.
- Use software that supports this file type. If one app does not work, try another compatible program for the same platform.
- Update the application if the file was created by a newer version of the software.
- Scan files from unknown sources before opening them, especially documents, archives, scripts, installers, and executable files.
What is a .fsx file?
File extension details and usage information
An FSX file is a source code script written in F# (pronounced F sharp), which is a functional-first, multi-paradigm programming language that is part of the .NET ecosystem. Unlike standard .NET source files (like .fs) that are typically compiled into assemblies such as DLLs or EXEs before execution, FSX files are designed to be executed as scripts using the F# Interactive (FSI) tool. This allows developers to run code snippets immediately without the overhead of creating a full project or performing a manual compilation step. FSX files are widely used for data science, prototyping, automation tasks, and exploratory programming. They support the full range of F# features, including pattern matching, type inference, and asynchronous programming. Because they are interpreted by the F# Interactive environment, they are excellent for iterative development where a programmer wants to test logic or visualize data in real-time. They often include special directives like #r to reference external libraries or #load to include other script files, making them highly flexible for complex scripting scenarios. The format is essentially plain text, allowing it to be managed easily with version control systems like Git.
Software Compatibility
Programs that may open or work with .fsx files
macOS
Compatible applications
Linux
Compatible applications
Mobile
Mobile applications
Can .fsx files be converted?
Options for saving or exporting this file to another format
In many cases, a .fsx file can be converted by opening it in compatible software and using an option such as Save As, Export, or Convert. The available output formats depend on the file type and the application used.
- Use the original software that created the file when possible.
- Check whether the application supports exporting to common formats.
- Be careful with online converters when working with private, business, or sensitive files.
- If conversion fails, the file may be corrupted, incomplete, encrypted, or not actually a .fsx file.
Why can't I open a .fsx file?
Common reasons this file type may not open correctly
Wrong software
The file may require a specific program that supports the .fsx format.
Incorrect extension
The file extension may have been renamed manually, even though the actual file format is different.
Corrupted file
The file may be incomplete, damaged during download, or transferred incorrectly.
Outdated app
Your software may need to be updated before it can open newer versions of this file format.
Frequently Asked Questions
Common questions about .fsx files
To open a .fsx file, use software that supports this file format.
- Visual Studio
- Visual Studio Code
- JetBrains Rider
- F# Interactive (fsi.exe)
- Dotnet CLI
Open the file in compatible software and look for options such as Save As, Export, or Convert. If no export option is available, the file may require a specialized converter or the original application that created it.
- Verify that the file extension is correct.
- Install or update compatible software.
- Try another application that supports this format.
- Check whether the file is corrupted, incomplete, or encrypted.
A file extension alone does not guarantee whether a file is safe or unsafe. Only open files from trusted sources, scan unknown files before opening them, and be especially careful with executable, script, archive, and document files.
File safety tips
Use caution with unknown files
Only open files from trusted sources. Before opening a .fsx file, scan it with antivirus software, verify that the file extension is expected, and avoid running unknown executable, installer, macro-enabled document, or script files.