This is a ZIM archive reader for browser extensions or add-ons, developed in HTML5/Javascript. You can get the extension from the Mozilla, Chrome and Edge extension stores (search for "Kiwix", or click on a badge below). There is a version implemented as an offline-first Progressive Web App (PWA) at https://moz-extension.kiwix.org/current/, primarily intended for use within the Mozilla Extension.
Once you have obtained an archive (see below), you can select it in Kiwix JS, and search for article titles. No further Internet access is required to read the archive's content. For example, you can have the entire content of Wikipedia in your own language inside your device (including images and audiovisual content) entirely offline. If your Internet access is expensive, intermittent, slow, unreliable, observed or censored, you can still have access to this amazing repository of knowledge, information and culture.
The reader also works with other content in the OpenZIM format: https://wiki.openzim.org/wiki/OpenZIM.