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Welcome to the website of JKP Application Development Services

What I do


I offer services pertaining to any aspect of Excel and VBA. My Services page shows you examples of services I provide. You will also find a list of recent projects there.


I develop bespoke Excel tools for customers and also Excel add-ins for the general public, like my spreadsheet auditing tool RefTreeAnalyser. Check out products I have developed.


I offer both pre-scheduled trainings and custom-made courses. Content of trainings can be adapted to your needs. If preferred we also offer any course as an in-house training.


Subscribe to our news letter or check out the archive. There is no set frequency, I just post something when I have time. In any case, it is all about Excel.

Free Excel tools

I develop custom-made applications using Microsoft Office Excel® and VBA and Access and VBA to their full extent. Have a look at various (free) downloads, some of which have become the de facto standard for Excel developers around the world.

Who is Jan Karel?

Would you like to learn more About me? On this page you can get to know me a little better and also find a short list of presentations I've given over the past years.

What's new on this site

English and/or Dutch content

Updated : Table Tools

I have updated the TableTools add-in. I'm updating the add-in so it also works on Mac Excel

Mon, 06 Jun 2022 10:45:00 GMT

Updated: Excel tips & tricks

I've added three new Excel and VBA tips and tricks to the Tips and tricks page today.

Fri, 03 Jun 2022 12:00:00 GMT

Updated : Flexfind

Flexfind has been updated: Some improvements to the UI and to Mac compatibility

Fri, 27 May 2022 13:15:00 GMT

Updated : Flexfind

Flexfind has been updated: Now allows search in autoshapes. New: Mac compatible!

Wed, 25 May 2022 15:45:00 GMT

Update: RefTreeAnalyser

RefTreeAnalyser has just been updated to version 3.0, build 177. RefTreeAnalyser now also enables you to add a table of external links to the Table Of Contents of your workbook.

Mon, 02 May 2022 10:15:00 GMT

Updated: Excel tips & tricks

I've added three new Excel and VBA tips and tricks to the Tips and tricks page today.

Wed, 20 Apr 2022 12:15:00 GMT

Updated: Enabling Drag and Drop between two Listboxes on a VBA Userform

I have updated the article about enabling drag and drop between two listboxes on an Excel userform with some improvements, like enabling multi-column listboxes. I've also fixed a couple of bugs.

Wed, 09 Mar 2022 13:20:00 GMT

New page: Excel tips & tricks

A new page featuring all sorts of Excel and VBA tips and tricks.

Fri, 25 Feb 2022 15:40:00 GMT

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