xllify

What is xllify?

An Excel add-in that turns plain-English descriptions into real, working custom functions, right inside Excel.

• Converts messy formulas and VBA into clean, named, reusable functions
• Generates actual add-in code that runs locally, your data stays on your machine
• Includes a standard library of common functions (regex, joins, lookups, and more)
• Runs on Windows (native multi-threaded XLL), Mac and web (WASM)

If nothing in the library fits, the coding assistant writes the code and helps you iterate, without leaving Excel.

Multiple runtimes

xllify generates JavaScript-based add-ins that run on Windows, Mac, and Excel for the web. This is Microsoft's modern, cross-platform approach to Excel extensibility, and the default output of xllify.

On Windows, xllify can also build native XLL add-ins using the Excel C SDK. XLLs run in-process with Excel and can offer significant advantages over web-based add-ins:

• Multi-threaded recalculation - Excel can call your functions across all available cores
• Near-zero call overhead - functions execute in-process, not across a web boundary
• Self-contained - a single file with no web server or internet connection required
• No dependency on a browser runtime or WebView

Both the web and XLL runtimes execute the same bytecode on the same VM, so functions need to be written only once and work identically on every platform, with no subtle differences.

Pricing

xllify is free to use for the creation and packaging of web-based add-ins. Native XLL builds, hosting for web-based Microsoft 365 add-ins, on-premises tooling, and industry-specific function packages are available under a yearly licence, payable monthly or annually. Deployment and distribution, including commercial use, incur no extra costs. Pricing details coming soon.

We are also available for consultancy on Excel add-in development. Get in touch.