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+This repository contains the available extension catalogues for the Tachiyomi app.
+
+[Download links to be added]
+
+### Writing an extension
+
+The easiest way to write and debug an extension is by directly hardcoding it in Tachiyomi's source code. Once it's working there, you have to clone this repository and create a new folder with a similar structure to the other catalogues. Then copy your catalogue implementation and make sure to change the package name if it was different in Tachiyomi. Finally, write the `build.gradle` file, which has the following structure:
+
+```gradle
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+
+ext {
+    appName = "Tachiyomi: My catalogue"
+    pkgNameSuffix = "lang.mycatalogue"
+    extClass = ".MyCatalogue"
+    extVersionCode = 1
+    extVersionSuffix = 1
+    libVersion = "1.0"
+}
+
+apply from: '../common.gradle'
+```
+
+* `appName` is the name of the Android application. By prefixing it with `Tachiyomi: `, it will be easier to locate with an Android package manager.
+* `pkgNameSuffix` has to be unique, and it's added to `eu.kanade.tachiyomi.extension`. The language and the site should be enough. Remember your catalogue code implementation must be placed in this package.
+* `extClass` points to the catalogue class. You can use a relative path starting with a dot (the package name is the base path). This is required for Tachiyomi to instantiate the catalogue.
+* `extVersionCode` is the version code of the catalogue and should be increased with any change to the implementation.
+* `extVersionSuffix` is the last part of the versioning.
+* `libVersion` is the version of the [extensions library](https://github.com/inorichi/tachiyomi-extensions-lib)* used. When this value is changed, `extVersionSuffix` should be reset to `1`. With the example used above, the version of the catalogue would be `1.0.1`.
+
+\* Note: this library only contains the method definitions so that the compiler can resolve them. The actual implementation is written in Tachiyomi.
+
+When everything is done, you can create the apk in Android Studio with `Build > Build APK` or `Build > Generate Signed APK`.
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