It’s a great pleasure for us to introduce Alwin Hoogerdijk, the founder of Alwin kindly shared with us the inspiring story of his business, which started as a hobby and, unexpectedly for him, grew into a company with a number of successful software products. Please read on to learn more about how it all started, what solutions Alwin and his team came up with, and their future plans.

At, we love to turn chaos into order. Our collection database apps and web-based software help our users to keep track of their book, movie, music, comic, and video game collections.

* History

We have been around since 1996 when I (Alwin Hoogerdijk, the founder of the company) created our first Windows program Music Collector. It started as a hobby project, for cataloging my own CD collection, but when I put it out there as “shareware”, many people started buying it. So in 2000 and 2001, I developed similar products for DVDs, books, comics, and video games. Initially, all of them were available as Windows programs only, but through the years, we branched out to mobile apps and web-based software.

For each collection type, we currently offer a “CLZ” mobile app and a Connect web-based program. E.g. for books, there is a CLZ Books mobile app (available for iOS and Android) and a Book Connect web-based program for use on Windows and Mac computers. Both can be used on their own, but they also work together seamlessly, syncing the database back and forth through our own CLZ Cloud solution.

For all five collection types, we run our own “Core” online database with item details (like cast and crew for movies, creator and key info for comics, track lists for CDs) and, of course, cover art, all indexed by barcode. So to catalog their collections, users can just scan the barcode on their collectibles and automagically get all details and images from our Core database downloaded to their app

Currently, (or CLZ for short) is a 12-man team located in Amsterdam, the Netherlands. The team consists of 5 developers, 4 content managers, 1 tester/support guy, and finally, my wife Sytske and me (Alwin) running the show :-).

* How CLZ uses ISBNdb

The CLZ Books mobile app and the Book Connect web application enable people to manage their book collections much more efficiently. The process of adding new books can’t be simpler – a user can just scan the book’s ISBN barcode or enter its title and author. The apps will instantaneously fetch the book details like cover art, author, title, etc. Of course, it’s possible to edit the data if necessary and specify such custom details as the book location (wardrobe, shelf, etc), owner, purchase price/date, and more.

Image Credit

For books, we run our own “Core” online book database that basically functions as a “cache” for book data, with the actual book data being retrieved from other online book data sources. ISBNdb has been our main book data source for almost five years.

Here’s how we use the ISBNdb API – when a user scans an ISBN barcode, a request goes to our server, and there, it first checks our own Core database to see if we have that ISBN listed and if the data is recent enough. If not, our server uses the ISBNdb API to retrieve the book data (and cover art) from the ISBNdb database. If that request is successful, which it usually is, that data is cached in our Core. The caching helps to keep the number of API requests (and subsequent costs) down to a minimum.

* What’s cooking?

Even after 27 years, our products are always under development, and we are still regularly releasing updates with new features, improvements, and small tweaks, always based on feedback from our users. For example, we just released the ability to use multi-level, tiered folders in the CLZ mobile apps.

In the future, we’d like to add a display of up-to-date market value for books and other exciting features to provide an even better experience for our customers. And we see ISBNdb as a long-term partner in our endeavors.

book data api