What is FCell?
FCell is an Excel Add-In which makes it very easy to use .NET to customize Excel both on application and document level. Create .NET User Defined Functions, custom ribbons and task panes. Use Reactive Extensions for real time spreadsheets, all without leaving Excel! FCell comes with built-in F#/C#/VB code editor and your customization source code is automatically saved with your workbook. No more VBA!
Powerful Type Conversions
FCell will automatically convert Excel data to/from any .NET primitive type, e.g. double, string, int, etc as well as 1 and 2 dimensional arrays of primitive types, Enums and more.
For types without built-in converter you can create your own custom conversion function. See Documentation for details.
If your user function returns F# async<'T> or is decorated with [XlAsync] attribute, it will run on a background thread without blocking Excel UI. This is a great feature for long running operations. You will see #WAIT while the function is running and you can keep using Excel as usual.
If your user function returns IObservable<'T>, it will subscribe to a stream of events. Creating real time spreadsheets has never been easier!
Custom Ribbon and Task Panes
Simply inherit from XlRibbon and define WinForms UserControl for your Task Pane. FCell will do the magic. No COM registration required!
Self contained workbook customization
Your customization source code is saved in your workbook and you can send it to anyone, just like a regular macro enabled workbook. FCell is only required to modify the code, but anyone can open and run the spreadsheet! No need to install anything, it only requires Excel and .NET 4.0. Magic!