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Custom Excel xll User Defined Function Development

Xll Series Contents

(note this is a work in progress - more pages will be added and linked too as and when we have time to complete them to an acceptable level)

Custom xll UDF service

Codematic develops custom xlls for clients who require the following features

  • Fast calculation
  • Secure Intellectual Property
  • Simple deployment
  • Simple maintenance and ongoing support

The service can be used to provide a single worksheet function, a group of worksheet functions, or a fully featured add-in with menus, toolbars, a range of commands and event handlers.

The process

Previous clients have usually provided a set of VBA functions or XLM functions to be converted, but we can work from a text specification or a set or worksheet cells if required.

Contact us with an idea of your requirements

We'll give you an idea of cost and expected delivery. If that is acceptable, we build and test the xll and email it for review. Once the client is happy they pay via our on-line shop.

All clients are provided with a full set of clear working source code (in C or C++). Our code does not depend on third party libraries or systems. You do not need anything other than a C++ editor/compiler (e.g. Visual Studio C++ Express 2008) and the freely available Microsoft Excel xll Software Developers Kit to change/adapt/extend our code.

How much?

Here are some indicative costs from previous projects to convert existing well written VBA to C xlls:

100 lines of array manipulation and calculations in VBA : 250 GBP

60 lines of Excel object model manipulation in VBA : 250 GBP

40 lines of Excel function equivalents in VBA : 200 GBP

A rough guide would be 250 GBP per function, assuming it is well written (ie reasonable size, uses Option Explicit, sensible variable names, etc)


You are free to distribute your xll and/or source code as you see fit, including incorporating into commercial products. Your clients need nothing more than Excel (any version - from 97 to 2007 inclusive) to use xlls.

Base project

Here is a base xll project (in C) to give you an idea. It contains a single UDF that takes two arguments and returns the total. It is in Visual Studio 6 format which every version since can open and translate fine. You do need a C/C++ version of Visual Studio though, like for example the free Visual C++ Express 2008. It requires the Excel SDK files (available free from the Microsoft site) be in the include path or the same folder.


If you require any more information please get in touch.



Upcoming Events:

25 January 2012 - UK Excel Developer Conference - London

Products for sale:


Office 2007 FileSearch replacement logo

New information about the missing FileSearch feature in Office 2007 and details of our pragmatic solution (Current price GBP 30.00)


worksheet password remover logo

Instant Excel worksheet protection remover and password recovery (Current price GBP 15.00)

Classic Ribbon Tab

classic ribbon for office 2007 logo

Add Excel 97/2000/2002/2003 compatible menu structure to Excel 2007
(Current Price GBP 10.00)


Products coming soon:

Link Manager

(Find and control external links in Excel Workbooks)

Due by Q1 2111.

XLAnalyst Pro

(Excel VBA based spreadsheet auditing tool)

Due before the end of 2111.

This page was last reviewed on December 21, 2011

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