The openZIM has been created almost 15 years ago. His primary goal was to specify a file based storage solution to efficiently store and access Wikipedia (Mediawiki) offline ; and then implement an official reader/writer software library came right after. The ZIM open spefication and the libzim are still at the core of the project. A few years later the ZIM tools have been launched to easily inspect and manipulate ZIM files on the command line.
But, over the following years, most of the project activity has grown around scrapers and we actively maintain more than 15 of them now. After a while, it has appeared that we should really start to mutualize code to avoid too much of duplicate code and rationalize maintenant. Therefore, a few libzim bindings and scraper libraries were created.