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Kiwix Android custom apps

Kiwix Android custom apps are Android apps running Kiwix for Android ZIM reader against a pre-configured ZIM file.

Kiwix publishes more than a dozen of such apps. Wikimed - Offline Medical Wikipedia and Wikivoyage - Offline Travel Guide being the most famous ones.

This project contains data and scripts needed to create specific custom Kiwix Android apps. It does not create the app, that's done separately by running the relevant Gradle command to build one or more custom apps.

License: GPL v3


This document is for end-users who are the publisher of new custom apps. If you are a developer and want to have an in-depth understanding about the custom apps, please read

Custom app folder

In the repository, each custom configuration is isolated in a so called custom app folder. If you need to create a new one for a new custom app, you can do that easily using Github UI. Go to, put the name of your app (no space, lowercase only) and add a slash at the end.

Description json file

The configuration of the custom app is handled using the info.json file which is in the custom app folder. Take example on an already existing one if you need to create a new custom app. The most important fields are:

  • app_name, the title of the app
  • zim_url, the ZIM online URL (to download to create the app)
  • enforced_lang, the language code of the content (and the app UI)

You can also create this new file using Github IO. Go to and type info.json.

Remark: If you make a simple update, just replace the zim_url with the latest available zim from Then comment your commit (e.g. "updated to YYYY-MM zim") and commit directly to master branch. You won't have to change anything more than this (just tagging the release, see below).

Icon master

The Icon master is file icon.png you find (or have to create) in the custom app folder. It is a square PNG file which is used as master to create the Icon set (see section below). This master has to match many constraints and you might even have to create an icon_foreground.png and icon_baground.png to achieve to do certain things. Look at the Android documentation about adaptive icons to know more.

Icon set

The Android custom app needs an Icon set to build properly. This Icon set is needed to properly show the app icon on user devices and is a list of bitmap pictures which are derivatives of an icon master.

To create this Icon set, follow these steps:

  1. Create a new empty project with Android Studio (add no activity > next > finish)
  2. In the project view (top left) there should be a dropdown that says Android select that and choose Project, this will make the project view display accurately to the file system
  3. Delete MyApplication/app/src/main/res
  4. Right click MyApplication/app in android studio, click New>Image Asset to open Asset Studio (if this option is greyed out you will have to wait for indexing to finish, this shouldn't take longer than 2 minutes)
  5. For foreground layer Source Asset > Asset Type choose Image
  6. For path click the folder icon and browse to the output of
  7. For background layer Source Asset > Asset Type choose Color
  8. Click on the color box
  9. This should present the color chooser, the box in the top right with the label # should be auto selected. Type FFFFFF to supply white as the color, this is typically the color used
  10. [Optional] go back to foreground layer and size the icon as appropriate with the slider
  11. Next > Finish will generate a res folder with all the icons needed in the location where you previously deleted the res folder.
  12. Cut and paste the res folder to kiwix-android-custom/whatever-directory-this-icon-set-is-for

These instructions are for a first time setup, you can reuse this project in the future for icon generation so many steps can be omitted.

Version name

The custom app will have a version name displayed on the Google Play store. This version name has to be a date in the format YYYY-MM (for example 2018-10. This version name should be the date of the content (neither the date of the Software nor the release date).

The app version name is determined in that order:

  1. The date can be hardcoded in the json file at the key version_name. Considering that this needs maintenance and that the publisher can easily create a discrepency with the ZIM content date, this should probably be avoided in most of the time.
  2. If nothing is specified in the json, then it tries to extract it from the ZIM file name. If the file - specified in zim_url - is wikipedia_en_all_maxi_2018-10.zim then it will be 2018-10.
  3. Otherwise the current date will be put (should be avoided).


Simply tag the repo in git with the name of a custom app eg wikimed. Go to the release tab and click on "Draft a new release". As "tag version" use the custom app folder name (e.g. wikimedar). Publish without adding a release title or description (not needed).

This triggers a Github action that will build an app using kiwix-android master branch and the icon set/json defined in this repository and then upload it to the Play Console in draft to alpha with an expansion file attached. Therefore, go to the Google Play Store Admin dashboard for the corresponding app and go to menu "Publication management" > "App version": under "Alpha", you can click on "Modify version". After a couple of hours the new version of the app should be listed in the public Play Store.

Remark: This will only work with app updates. To create a new custom app an app must be built manually and submit to the Google Play store


GPLv3 or later, see LICENSE for more details.

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