Grab a dev key here · · Other install options
Get started with xllify Assistant, then use Build > Export to continue locally.
Alternatively, create a repo from the local-starter template with Claude Code support.
Create your custom functions directly in Excel
Work in Claude Code, if you'd prefer
Who is this for?
Data & software vendors
You already have the product, so it is not a huge reach to give your customers native Excel functions that pull your data or run your models live in their spreadsheets. An additional revenue stream and no C++ or .NET to maintain.
Analysts & finance teams
You have calculations that live in formulas spread across hundreds of cells. Package them as functions your team calls by name: consistent, auditable, impossible to accidentally overwrite.
Trading desks
You're fielding need-this-yesterday requests from traders. Capture their requirements, test, and roll out fast. Every desk gets the same locked-down logic running at native speed.
Not enough hours in the day? We work with teams on a consultancy basis to deliver add-ins end to end. Because we built (and use!) xllify, delivery time and cost tend to be a lot lower than you'd expect. Get in touch.
Custom functions vs formulas
Formulas are the right tool most of the time. Custom functions extend what's possible, unlocking benefits that formulas alone can't provide.
Your logic in code, not cells
Store functions in files, version them in git, test before you deploy. Everything your team already does for software, now for your Excel logic too.
Process data outside Excel
Pull from APIs, query databases, or run heavy calculations elsewhere. Your function returns only the result.
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.
Distributable and self-contained
Package your functions into a single installable file. No formulas to copy between workbooks, no risk of them breaking in transit.
What xllify provides
Rapid results at any skill level
Write code directly, get a helping hand where you need it, or describe what you want and iterate from there.
Verified standard library
Common operations are pre-built and optimised, not hallucinated. Suggestions draw on this library first, so output is higher quality and your own functions can use them too. More
Remote builds
Built and packaged in seconds via the cloud, including XLL builds for Windows. No Windows machine required. The CLI is optional; builds always go through the remote service.
Cross-platform runtime
Your add-ins can run on Windows, Mac and Excel for the web. Native on Windows for extra performance.
Desktop-speed calculations
Native Windows add-ins run at full speed inside Excel. Multi-threaded, single-file, no server required.
Safe to share
Native builds can't access your files or network. The sandboxed design means they're safe to distribute.
Try instantly in Excel for the web
Preview your functions in Excel for the web without installing anything. We handle the hosting.
Yours to own
No phone home, no analytics, no per-seat licences. Rebuild and update as often as you need.
See how xllify compares to similar offerings →
Pricing
Free
- Build in your browser or Excel
- Office add-in hosted previews and downloadable builds
- Native XLL builds with 30-day expiry
- AI assistant included
- xllify standard library access
- Support for xllify issues
- Personal, non-commercial, non-profit use only
Early adopter
- Permanent XLL builds
- No xllify branding
- Multiple add-in projects
- Higher AI coding assistance usage rates
- Priority email support for xllify issues
- Distribute to unlimited end users
Thank you! After clicking, sign in with your preferred account (Google, GitHub, or Microsoft). You'll land on your Account page where you'll find the button to complete your one-off payment.
xllify is built and maintained by one person. New features are shipping regularly. We'll be in touch personally after you sign up.
Roadmap
Included as they land, initially for early adopter subscribers.
Local development
Build and test add-ins locally without the remote build service. Full CLI and toolchain for teams that prefer to work offline or integrate into their own CI pipeline.
External data
Pull live data from APIs and databases directly into your functions. HTTP requests, SQL queries, and common data sources available from within your Luau scripts.
RPC
Call out to local or remote services from Excel functions. Expose any backend logic as a custom function without running computation inside the add-in itself.
Office Add-in hosting with Microsoft Entra auth
Host your Office Add-in through xllify with Microsoft Entra authentication, so you can deploy to your organisation without managing your own web server or manifest.
Async functions
Run long calculations without blocking Excel recalculation. Return results when ready, keeping your spreadsheet responsive while work happens in the background.
RTD / streaming
Push live values directly into Excel cells. Pre-written integrations with common brokers and streaming data services, or connect your own source.