Opening an FSI File

The FSI file type is primarily associated with FSIViewer.

FSIFile Extension FSI
File extension: FSI
File type:  container file

What is an FSI file?

FSI files mostly belong to FSIViewer. FSI files come in two main types. Some use the Microsoft Compound format to store file system integration details, sometimes called ODBC Script Files. These files contain multiple data streams that hold integration data and system instructions. They are usually opened with a dedicated tool such as FSIViewer.
  • Microsoft Compound FSI files: Store integration data in a container format that allows the file to embed several data streams. They are part of workflows that use ODBC scripting.
  • ZIP-based FSI files: Serve as packages for CODESYS applications, bundling control configurations and resources. More information is available on the Codesys website.
  • FilExt.com tip: Each type is designed to supply configuration or script data for its respective system environment.

    How to open an FSI file

    You need a suitable software like FSIViewer to open an FSI file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your FSI file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a FSI file directly in the browser:. Just drag the file onto this browser window and drop it.

    Online FSI Text Viewer

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    Programs that open and convert FSI files:

    1. FSIViewer
      See the previous paragraphs to learn more about the main application. FSI files are often referred to as FSIViewer data files because this type of file is primarily created or used by this software.
    2. F# (Source Code) by Microsoft Corporation
      F# (pronounced F Sharp) is a scalable, succinct, type-safe, type-inferred, efficiently executing functional/imperative/object-oriented programming language. It aims to be the premier type-safe functional programming language for the .NET framework and other implementations of the Ecma 335 Common Language Infrastructure specification. F# was partially inspired by the OCaml language and shares some common core constructs with it. The inputs to the F# compiler or the F# Interactive dynamic compiler consist of source code files, with extensions .fs, .fsi, .ml, .mli, .fsx, .fsscript. Files with extension .fs, .ml must conform to grammar element implementation-file. Files with extension .fsi, .mli must conform to grammar element signature-file.  Files with extension .fsx and .fsscript are processed just as for those with extension .fs except that the conditional compilation symbol INTERACTIVE is defined instead of COMPILED, the assembly FSharp.Compiler.Interactive.Settings.dll is referenced by default, and the namespace Microsoft.FSharp.Compiler.Interactive.Settings is opened by default. This file format is classified as Source Code. Related links: F# Download, Exploring the FSharp Language Series
    3. FileSplit

    Technical Data for FSI File Extension

    File classification:
    Data
    Related files:
    ppt, f%23, fsx, mli, fsscript, doc, xls, mdb, zip, cab
    Mime type:

    an fsi container file is a special file format and should only be edited and saved with the appropriate software.

    How to solve problems with FSI files

    • Associate the FSI file extension with the correct application.
    • Update your software that should actually open container files. Because only the current version supports the latest FSI file format. Search, therefore, e.g. on the manufacturer website after an available FSIViewer update.
    • To make sure that your FSI file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
    • Click here to open your .FSI file online - secure, fast, and no downloads needed.
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