Why use custom functions over formulas?
Centralise your logic
Stop copying formulas down columns. Define it once, use it everywhere. Cleaner sheets, less room for error.
Easier to audit
One definition to review instead of hundreds of cells. Find and fix errors in one place.
Faster to change
Fix or improve the function, rebuild, and every sheet that uses it is updated. Test your logic outside of Excel before deploying.
Share or sell
Package your functions into a single add-in. Deploy internally, share with colleagues, or sell the expertise you've built into it.
xllify provides...
AI assistant
Describe what you need in plain English, or paste formulas and VBA.
Verified standard library
AI will always try to use the included tested implementations before generating new code.
Remote builds
Nothing to install. Built and packaged in seconds, no local tooling required.
Cross-platform runtime
One codebase runs on Windows, Mac and Excel for the web. Accelerated on Windows.
Native XLL performance
XLLs run in-process with Excel. Multi-threaded recalculation, single-file deployment.
Sandboxed execution
Native builds have no network or filesystem access. The sandboxed design ensures safety.
Hosted preview
Office add-ins are hosted for you. Preview your functions in Excel for the web without any setup.
Portable output
Download a ready-to-run add-in. Sell it, share it, or deploy it internally.
What is xllify?
xllify is a platform for creating custom Excel functions. Describe what you need in a prompt, or write code directly. Work in the browser, in Excel via the xllify Assistant add-in, or locally with the xllify agent (coming soon).
xllify prioritises verified, tested implementations from the standard library before generating new code. The standard library includes native C++ primitives for performance-critical operations, available to every function, including those generated by AI. The runtime is available for Windows, Mac and Web.
Native XLL runtime
In addition to cross-platform web add-ins, xllify can build native XLL add-ins for Windows. XLLs run in-process with Excel with multi-threaded recalculation, self-contained in a single file with no web server or internet connection required. No local tooling needed: xllify handles everything through a remote build service.
Function code runs in a sandboxed VM with no access to the network or file system, so XLLs built with xllify cannot be used as an attack vector. Both runtimes execute the same bytecode, so functions work identically everywhere.
XLL builds are in preview and available to all users. Builds expire after thirty days.
Remote build service
xllify compiles and packages your add-ins in the cloud. Nothing to install. Write your functions in the browser or in Excel, and xllify produces a ready-to-use add-in in seconds. This applies to both Office Add-ins (WASM) and native XLL builds for Windows. Fair use applies.
Pricing
xllify is free to use. Web add-ins can be created and packaged at no cost. Native XLL builds are available to all users and expire after thirty days. Pricing details coming soon.
We are also available for consultancy on Excel add-in development. Get in touch.