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Contributing

This guide has some instructions and tips on how to create a new Keiyoushi extension. Please read it carefully if you're a new contributor or don't have any experience on the required languages and knowledges.

This guide is not definitive and it's being updated over time. If you find any issues in it, feel free to report it through a Meta Issue or fixing it directly by submitting a Pull Request.

Table of Contents

  1. Prerequisites
    1. Tools
    2. Cloning the repository
  2. Getting help
  3. Writing an extension
    1. Setting up a new Gradle module
    2. Loading a subset of Gradle modules
  4. Core dependencies
    1. Extension main class
    2. HTML and Image Processing
    3. OkHttp and Network
    4. Extension call flow
    5. Misc notes
    6. Advanced Extension features
  5. Multi-source themes
    1. Creating a new theme
    2. Using a Theme
  6. Running
  7. Debugging
    1. Android Debugger
    2. Logs
    3. Inspecting network calls
    4. Using external network inspecting tools
  8. Building
  9. Submitting the changes
    1. Pull Request checklist

Prerequisites

Before you start, please note that the ability to use following technologies is required and that existing contributors will not actively teach these to you.

Tools

Cloning the repository

Some alternative steps can be followed to skip unrelated sources, which will make it faster to pull, navigate and build. This will also reduce disk usage and network traffic.

Due to the large size of this repository, it is highly recommended to do a partial clone to save network traffic and disk space.

Steps

  1. Do a partial clone.

    git clone --filter=blob:none --sparse <fork-repo-url>
cd extensions-source/

  2. Configure sparse checkout.

    There are two modes of pattern matching. The default is cone (🔺) mode. Cone mode enables significantly faster pattern matching for big monorepos and the sparse index feature to make Git commands more responsive. In this mode, you can only filter by file path, which is less flexible and might require more work when the project structure changes.

    You can skip this code block to use legacy mode if you want easier filters. It won't be much slower as the repo doesn't have that many files.

    To enable cone mode together with sparse index, follow these steps:

    git sparse-checkout set --cone --sparse-index
# add project folders
git sparse-checkout add buildSrc core gradle lib lib-multisrc utils
# add a single source
git sparse-checkout add src/<lang>/<source>

    To remove a source, open .git/info/sparse-checkout and delete the exact lines you typed when adding it. Don't touch the other auto-generated lines unless you fully understand how cone mode works, or you might break it.

    To use the legacy non-cone mode, follow these steps:

    # enable sparse checkout
git sparse-checkout set --no-cone
# edit sparse checkout filter
vim .git/info/sparse-checkout
# alternatively, if you have VS Code installed
code .git/info/sparse-checkout

    Here's an example:

    /*
!/src/*
!/multisrc-lib/*
# allow a single source
/src/<lang>/<source>
# allow a multisrc theme
/lib-multisrc/<source>
# or type the source name directly
<source>

    Explanation: the rules are like gitignore. We first exclude all sources while retaining project folders, then add the needed sources back manually.

  3. Configure remotes.

    # add upstream
git remote add upstream <keiyoushi-repo-url>
# optionally disable push to upstream
git remote set-url --push upstream no_pushing
# optionally fetch main only (ignore all other branches)
git config remote.upstream.fetch "+refs/heads/main:refs/remotes/upstream/main"
# update remotes
git remote update
# track main of upstream instead of fork
git branch main -u upstream/main

  4. Useful configurations. (optional)

    # prune obsolete remote branches on fetch
git config remote.origin.prune true
# fast-forward only when pulling main branch
git config pull.ff only
# Add an alias to sync main branch without fetching useless blobs.
# If you run `git pull` to fast-forward in a blobless clone like this,
# all blobs (files) in the new commits are still fetched regardless of
# sparse rules, which makes the local repo accumulate unused files.
# Use `git sync-main` to avoid this. Be careful if you have changes
# on main branch, which is bad practice.
git config alias.sync-main '!git switch main && git fetch upstream && git reset --keep FETCH_HEAD'

  5. Later, if you change the sparse checkout filter, run git sparse-checkout reapply.

Read more on Git's object model, partial clone, sparse checkout, sparse index, and negative refspecs.

Getting help

  • Join the Discord server for online help and to ask questions while developing your extension. When doing so, please ask them in the #programming channel.
  • There are some features and tricks that are not explored in this document. Refer to existing extension code for examples.

Writing an extension

The quickest way to get started is to copy an existing extension's folder structure and renaming it as needed. We also recommend reading through a few existing extensions' code before you start.

Setting up a new Gradle module

Each extension should reside in src/<lang>/<mysourcename>. Use all as <lang> if your target source supports multiple languages or if it could support multiple sources.

The <lang> used in the folder inside src should be the major language part. For example, if you will be creating a pt-BR source, use <lang> here as pt only. Inside the source class, use the full locale string instead.

Loading a subset of Gradle modules

By default, all individual and multisrc extensions are loaded for local development. This may be inconvenient and can drastically slow down your system when working on a single extension.

To adjust which modules are loaded, make adjustments to the settings.gradle.kts file as needed. You can specify the single extension you want to work on in the load individual extension function. This helps avoid loading unnecessary modules, making the build process more efficient and preventing your CPU from being overworked.

Extension file structure

The simplest extension structure looks like this:

$ tree src/<lang>/<mysourcename>/
src/<lang>/<mysourcename>/
├── AndroidManifest.xml (optional)
├── build.gradle
├── res
│   ├── mipmap-hdpi
│   │   └── ic_launcher.png
│   ├── mipmap-mdpi
│   │   └── ic_launcher.png
│   ├── mipmap-xhdpi
│   │   └── ic_launcher.png
│   ├── mipmap-xxhdpi
│   │   └── ic_launcher.png
│   └── mipmap-xxxhdpi
│       └── ic_launcher.png
└── src
    └── eu
        └── kanade
            └── tachiyomi
                └── extension
                    └── <lang>
                        └── <mysourcename>
                            ├── <MySourceName>.kt
                            ├── <Dto>.kt (optional)
                            ├── <Filters>.kt (optional)
                            └── <UrlActivity>.kt (optional)

<lang> should be an ISO 639-1 compliant language code (two letters or all). <mysourcename> should be adapted from the site name, and can only contain lowercase ASCII letters and digits. Your extension code must be placed in the package eu.kanade.tachiyomi.extension.<lang>.<mysourcename>.

Tip

Additional files in the extension package (like Dto.kt, Filters.kt, UrlActivity.kt) should NOT repeat the extension name (e.g. use Dto.kt instead of MySourceNameDto.kt). Note: While older extensions might use the repeated name pattern, avoiding it is a newly enforced convention to maintain consistency across the repository.

AndroidManifest.xml (optional)

You only need to create this file if you want to add deep linking to your extension. See URL intent filter for more information.

build.gradle

Make sure that your new extension's build.gradle file follows the following structure:

ext {
    extName = '<My source name>'
    extClass = '.<MySourceName>'
    extVersionCode = 1
    isNsfw = true
}

apply from: "$rootDir/common.gradle"
Field Description
extName The name of the extension. Should be romanized if site name is not in English.
extClass Points to the class that implements Source. You can use a relative path starting with a dot (the package name is the base path). This is used to find and instantiate the source(s).
extVersionCode The extension version code. This must be a positive integer and incremented with any change to the code.
isNsfw (Optional, defaults to false) Flag to indicate that a source contains NSFW content.

The extension's version name is generated automatically by concatenating 1.4 and extVersionCode. With the example used above, the version would be 1.4.1.

Core dependencies

Extension API

Extensions rely on extensions-lib, which provides some interfaces and stubs from the app for compilation purposes. The actual implementations can be found here. Referencing the actual implementation will help with understanding extensions' call flow.

lib tools

The lib/ directory contains reusable Gradle modules that solve common problems shared across multiple extensions, such as cookie injection, image descrambling, JavaScript deobfuscation, and more. Before implementing something from scratch, check whether an existing lib already covers your use case. Each lib is self-documented via KDoc comments and/or a README in its own folder.

Available libs

Module Description
lib-cookieinterceptor Injects cookies into OkHttp requests for a given domain
lib-cryptoaes AES-CBC decryption compatible with CryptoJS; JSFuck deobfuscation
lib-randomua Fetches and rotates real-world User-Agent strings
lib-synchrony JavaScript deobfuscation via the Synchrony engine (QuickJS sandbox)
lib-textinterceptor Renders plain text or HTML as a PNG image page
lib-unpacker Unpacks Dean Edwards-packed JavaScript; substring extraction helpers

Note

The table above highlights the most commonly used libraries. Check the lib/ directory for the full list of available modules and their specific READMEs.

Adding a lib dependency

Declare the module in your extension's build.gradle:

dependencies {
    implementation(project(':lib:<name>'))
}

For example:

dependencies {
    implementation(project(':lib:dataimage'))
}

Gradle resolves transitive dependencies automatically, so you only need to declare the lib you are directly using.

Creating a new lib

If no existing lib fits your needs and the functionality is generic enough to be shared across multiple extensions, you can create a new one.

A lib follows this structure:

lib/<mylibname>/
├── build.gradle.kts
└── src
    └── keiyoushi
        └── lib
            └── <mylibname>
                └── MyLib.kt

The build.gradle.kts must apply the lib-android plugin:

plugins {
    id("lib-android")
}

If your lib depends on another lib, declare it in the same file:

plugins {
    id("lib-android")
}

dependencies {
    implementation(project(":lib:<other-lib>"))
}

Place your code in the package keiyoushi.lib.<mylibname>. Document public API with KDoc so contributors can understand the lib without needing to read CONTRIBUTING.md.

keiyoushi.utils (core utilities)

The core/utils module provides a set of shared extension functions that are available to all extensions without any extra Gradle dependency. Prefer using these helpers instead of implementing your own equivalents, as they provide standardized and maintained solutions. The utilities live in the keiyoushi.utils package and are imported individually.

JSON parsing - parseAs

Use keiyoushi.utils.parseAs to deserialize JSON. It works on String, Response, InputStream, and JsonElement receivers and uses the shared jsonInstance (a pre-configured Json with ignoreUnknownKeys = true). The Response and InputStream variants use efficient stream decoding and automatically close the stream after reading.

import keiyoushi.utils.parseAs

// From a Response (uses streaming and consumes the body):
val dto = response.parseAs<MyDto>()

// From a String:
val dto = jsonString.parseAs<MyDto>()

// With a transform applied before parsing (e.g., stripping JSONP callbacks):
val dto = response.parseAs<MyDto> { it.substringAfter("callback(").dropLast(1) }

Do not create a local private val json: Json by injectLazy() unless you specifically need a custom JSON configuration (e.g., isLenient = true or custom serializers). For standard parsing, the global instance is already available via jsonInstance and the parseAs helpers use it automatically.

JSON serialization - toJsonString / toJsonRequestBody

Use keiyoushi.utils.toJsonString to serialize an object to a JSON string. If you are sending a POST/PUT request, use keiyoushi.utils.toJsonRequestBody to directly convert your object into an OkHttp RequestBody with the correct application/json media type.

import keiyoushi.utils.toJsonRequestBody
import keiyoushi.utils.toJsonString

// To a RequestBody for OkHttp (recommended for APIs):
val body = myRequestDto.toJsonRequestBody()

// To a simple String:
val jsonString = myRequestDto.toJsonString()
JSON models (DTOs) and serialization

When defining @Serializable classes for JSON parsing, do not use data class unless you actually need data class features (like copy() or destructuring). Use a regular class instead to reduce the generated bytecode size.

Always use camelCase for Kotlin properties. Only use @SerialName when the JSON key does not match the property name (e.g., mapping a snake_case JSON key like cover_img to coverImg, or an invalid Kotlin identifier like _count to count). If the JSON key already matches the property name exactly, @SerialName is redundant and should be omitted. It is also recommended to make fields private if they are only used internally (for instance, when mapping directly to SManga or SChapter within the DTO).

import kotlinx.serialization.SerialName
import kotlinx.serialization.Serializable

// Bad: Using data class and snake_case variable names
@Serializable
data class MyDto(val manga_id: Int, val cover_img: String)

// Good: Regular class, camelCase variables mapped with @SerialName only when names differ, and private fields
@Serializable
class MyDto(
    @SerialName("manga_id") private val mangaId: Int,
    @SerialName("cover_img") private val coverImg: String,
    private val title: String, // No @SerialName needed if JSON key is "title"
    @SerialName("_count") private val count: Int, // Needed for invalid Kotlin identifiers
) {
    fun toSManga() = SManga.create().apply {
        url = mangaId.toString()
        thumbnail_url = coverImg
        this.title = title
    }
}
Protobuf parsing and serialization — parseAsProto / toRequestBodyProto

If a source's API uses Protocol Buffers (Protobuf) instead of JSON, use the keiyoushi.utils helpers to decode and encode the data. These extensions use a shared protoInstance and automatically handle resource management.

import keiyoushi.utils.parseAsProto
import keiyoushi.utils.toRequestBodyProto
import keiyoushi.utils.decodeProtoBase64

// From a Response (automatically closes the body):
val dto = response.parseAsProto<MyProtoDto>()

// From a Response with a transform applied before decoding:
val dto = response.parseAsProto<MyProtoDto> { bytes -> bytes.drop(4).toByteArray() }

// Decoding a Base64-encoded Protobuf string:
val dto = base64String.decodeProtoBase64<MyProtoDto>()

// Creating a RequestBody for a POST request (defaults to application/protobuf):
val requestBody = myRequestDto.toRequestBodyProto()

If you only need to work with raw bytes, you can also use .decodeProto() and .encodeProto() directly on a ByteArray.

Do not create a local private val proto: ProtoBuf by injectLazy() unless you specifically need a custom configuration. For standard parsing, the global instance is already available and the parseAsProto helpers use it automatically.

Date parsing - tryParse

Use keiyoushi.utils.tryParse on a SimpleDateFormat instance to safely parse a date string. It returns 0L on failure or when the input is null, which is exactly what the app expects.

import keiyoushi.utils.tryParse

// Declare dateFormat at class/file level - creating SimpleDateFormat is expensive:
private val dateFormat = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.ROOT).apply {
    timeZone = TimeZone.getTimeZone("UTC")
}

chapter.date_upload = dateFormat.tryParse(dateStr)

Do not write manual try/catch blocks or null-guards around SimpleDateFormat.parse() - tryParse handles both. Also, always declare your SimpleDateFormat as a class-level or file-level val so it is not reconstructed for every chapter.

Filter helpers - firstInstance / firstInstanceOrNull

Use these instead of filterIsInstance<T>().first() / filterIsInstance<T>().firstOrNull().

import keiyoushi.utils.firstInstance
import keiyoushi.utils.firstInstanceOrNull

val genreFilter = filters.firstInstanceOrNull<GenreFilter>()

SharedPreferences - getPreferences / getPreferencesLazy

Use these instead of accessing Injekt manually.

import keiyoushi.utils.getPreferences
import keiyoushi.utils.getPreferencesLazy

// Eager:
private val preferences = getPreferences()

// Lazy (recommended for most cases):
private val preferences by getPreferencesLazy()
Next.js data extraction - extractNextJs / extractNextJsRsc

If the site is built with Next.js, use keiyoushi.utils.extractNextJs on a Document or Response, or keiyoushi.utils.extractNextJsRsc on a raw RSC response string to pull typed data out of the hydration payload without fragile HTML scraping.

import keiyoushi.utils.extractNextJs

val data = response.extractNextJs<MyDto>()
// Or with an explicit predicate:
val data = document.extractNextJs<MyDto> { element ->
    element is JsonObject && "slug" in element
}

For client-side navigation responses (text/x-component content type), pass the rsc: 1 request header and use extractNextJsRsc on the response body string. See #14266 and #14446 for real-world usage.

Extracting URLs - setUrlWithoutDomain + absUrl

When extracting URLs from HTML, prefer element.absUrl("href") or element.attr("abs:href") over manually concatenating baseUrl + path. Combined with setUrlWithoutDomain(), this safely handles both absolute and relative links.

Additional dependencies

If you find yourself needing additional functionality, you can add more dependencies to your build.gradle file. Many of the dependencies from the app are exposed to extensions by default.

Note

Several dependencies are already exposed to all extensions via Gradle's version catalog. To view which are available check the gradle/libs.versions.toml file.

Notice that we're using compileOnly instead of implementation if the app already contains it. You could use implementation instead for a new dependency, or you prefer not to rely on whatever the main app has at the expense of app size.

Important

Using compileOnly restricts you to versions that must be compatible with those used in the latest stable version of the app.

Extension main class

The class which is referenced and defined by extClass in build.gradle. This class should implement either SourceFactory or HttpSource.

Class Description
SourceFactory Used to expose multiple Sources. Use this in case of a source that supports multiple languages or mirrors of the same website.
HttpSource For online source, where requests are made using HTTP.
ParsedHttpSource Deprecated, use HttpSource instead.

Main class key variables

Field Description
name Name displayed in the "Sources" tab in the app.
baseUrl Base URL of the source without any trailing slashes.
lang An ISO 639-1 compliant language code (two letters in lower case in most cases, but can also include the country/dialect part by using a simple dash character).
id Identifier of your source, automatically set in HttpSource. It should only be manually overridden if you need to copy an existing autogenerated ID.

HTML and Image Processing

  • Parsing partial HTML: If an API returns a JSON response containing an HTML string, use Jsoup.parseBodyFragment(html, baseUrl) instead of Jsoup.parse(html). Passing the baseUrl ensures that abs:href and absUrl() can correctly resolve relative links.

  • Formatting Chapter Numbers: Do not write custom DecimalFormat logic just to remove trailing zeros from float chapter numbers. Simply use .toString().removeSuffix(".0").

  • Generating Page lists: The app ignores the index passed to the Page object, but you must ensure the list itself is sorted correctly according to the source. You can use Kotlin's mapIndexed to easily instantiate Page objects, or rely on the index provided by the source API if available:

    return document.select(".pages img").mapIndexed { index, img ->
    Page(index, imageUrl = img.attr("abs:src"))
}

  • Memory-efficient Image Interceptors: When implementing interceptors for descrambling, stitching, or decrypting images, avoid loading the entire image into a ByteArray, as this can cause OutOfMemoryError on low-end devices. Prefer stream-based processing instead:

    • Read: Use response.body.byteStream() with BitmapFactory.decodeStream() to decode images directly from the stream.
    • Write: Write the processed bitmap into an Okio Buffer via output.outputStream() and convert it using asResponseBody(mediaType).
    • Decryption: Use Okio's cipherSource extension for stream-based decryption rather than decrypting a full byte array in memory.
    • Note: readByteArray() should generally be avoided here because it forces full in-memory buffering of the image. Streaming directly keeps memory usage lower and more stable.
    • Always wrap network responses in response.use { ... } to ensure the response body is properly closed and to prevent memory leaks.
    • If applicable, call bitmap.recycle() after you're done with it to free native memory early.

OkHttp and Network

  • GraphQL Queries: If you are sending GraphQL requests, use Kotlin's raw multi-dollar string interpolation ($$"""...""") for your queries. This prevents having to escape every JSON variable $ symbol manually.

  • Empty checks on .text(): Because Jsoup's .text() automatically trims whitespace, you can use .isNotEmpty() instead of .isNotBlank() when checking for empty strings.

Extension call flow

Popular Manga

a.k.a. the Browse source entry point in the app (invoked by tapping on the source name).

  • The app calls fetchPopularManga which should return a MangasPage containing the first batch of found SManga entries.
    • This method supports pagination. When user scrolls the manga list and more results must be fetched, the app calls it again with increasing page values (starting with page=1). This continues while MangasPage.hasNextPage is passed as true and MangasPage.mangas is not empty.
  • To show the list properly, the app needs url, title and thumbnail_url. You must set them here. The rest of the fields could be filled later (refer to Manga Details below).

Latest Manga

a.k.a. the Latest source entry point in the app (invoked by tapping on the "Latest" button beside the source name).

  • Enabled if supportsLatest is true for a source
  • Similar to popular manga, but should be fetching the latest entries from a source.

Manga Search

  • When the user searches inside the app, fetchSearchManga will be called and the rest of the flow is similar to what happens with fetchPopularManga.
    • If search functionality is not available, return Observable.just(MangasPage(emptyList(), false))
  • getFilterList will be called to get all filters and filter types.
Filters

The search flow has support for filters that can be added to a FilterList inside the getFilterList method. When the user changes the filters' state, they will be passed to the searchRequest, and they can be iterated to create the request (by getting the filter.state value, where the type varies depending on the Filter used). You can check the filter types available here and in the table below.

Filter State type Description
Filter.Header None A simple header. Useful for separating sections in the list or showing any note or warning to the user.
Filter.Separator None A line separator. Useful for visual distinction between sections.
Filter.Select<V> Int A select control, similar to HTML's <select>. Only one item can be selected, and the state is the index of the selected one.
Filter.Text String A text control, similar to HTML's <input type="text">.
Filter.CheckBox Boolean A checkbox control, similar to HTML's <input type="checkbox">. The state is true if it's checked.
Filter.TriState Int A enhanced checkbox control that supports an excluding state. The state can be compared with STATE_IGNORE, STATE_INCLUDE and STATE_EXCLUDE constants of the class.
Filter.Group<V> List<V> A group of filters (preferentially of the same type). The state will be a List with all the states.
Filter.Sort Selection A control for sorting, with support for the ordering. The state indicates which item index is selected and if the sorting is ascending.

All control filters can have a default state set. It's usually recommended, if the source has filters to make the initial state match the popular manga list. This way, when the user opens the filter sheet the state accurately represents the currently displayed manga.

The Filter classes can also be extended, so you can create new custom filters like the UriPartFilter:

open class UriPartFilter(displayName: String, private val vals: Array<Pair<String, String>>) :
    Filter.Select<String>(displayName, vals.map { it.first }.toTypedArray()) {
    fun toUriPart() = vals[state].second
}

Manga Details

  • When user taps on a manga, getMangaDetails and getChapterList will be called and the results will be cached.
    • A SManga entry is identified by it's url.
  • getMangaDetails is called to update a manga's details from when it was initialized earlier.
    • SManga.initialized tells the app if it should call getMangaDetails. If you are overriding getMangaDetails, make sure to pass it as true.
    • SManga.genre is a string containing list of all genres separated with ", ".
    • SManga.status is an "enum" value. Refer to the values in the SManga companion object.
    • During a backup, only url and title are stored. To restore the rest of the manga data, the app calls getMangaDetails, so all fields should be (re)filled in if possible.
    • If a SManga is cached, getMangaDetails will be only called when the user does a manual update (Swipe-to-Refresh).
  • getChapterList is called to display the chapter list.
    • The list should be sorted descending by the source order.
  • getMangaUrl is called when the user taps "Open in WebView".
    • If the source uses an API to fetch the data, consider overriding this method to return the manga absolute URL in the website instead.
    • It defaults to the URL provided to the request in mangaDetailsRequest.

Chapter

  • SChapter.date_upload is the UNIX Epoch time expressed in milliseconds.

    • If you don't pass SChapter.date_upload and leave it zero, the app will use the default date instead, but it's recommended to always fill it if it's available.

    • To get the time in milliseconds from a date string, you can use a SimpleDateFormat like in the example below.

      import keiyoushi.utils.tryParse

chapter.date_upload = dateFormat.tryParse(dateStr)

private val dateFormat by lazy {
    SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.ENGLISH)
}

      Make sure you make the SimpleDateFormat a class constant or variable so it doesn't get recreated for every chapter. If you need to parse or format dates in manga description, create another instance since SimpleDateFormat is not thread-safe.

    • If the parsing has any problems, make sure to return 0L so the app will use the default date instead.

    • The app will overwrite dates of existing old chapters UNLESS 0L is returned.

    • If the source only provides the manga's updated date, assign it to the latest chapter only.

  • getChapterUrl is called when the user taps "Open in WebView" in the reader.
    • If the source uses an API to fetch the data, consider overriding this method to return the chapter absolute URL in the website instead.
    • It defaults to the URL provided to the request in pageListRequest.

Chapter Pages

  • When user opens a chapter, getPageList will be called and it will return a list of Pages.
  • While a chapter is open in the reader or is being downloaded, fetchImageUrl will be called to get the URL for each page of the manga if Page.imageUrl is empty.
  • If the source provides all the Page.imageUrls directly, you can fill them and leave Page.url empty, so the app will skip the fetchImageUrl step and directly call fetchImage.
  • The Page.url and Page.imageUrl attributes should be set as absolute URLs.
  • The list of Pages should be returned already sorted, the index field is ignored.
  • If you need to pass additional data to the image fetcher, it is recommended to pass it as a URL fragment (e.g. url + "#data"). OkHttp does not send fragments to the server, so there is no need to strip it out afterwards.

Misc notes

  • Use asJsoup(): Instead of manually reading the response body and parsing it with Jsoup (Jsoup.parse(response.body.string())), use the app's built-in extension function: response.asJsoup() (requires eu.kanade.tachiyomi.util.asJsoup).
  • Jsoup .text() is already trimmed: Calling element.text().trim() is redundant because Jsoup automatically normalizes and trims whitespace. Just use element.text().
  • Use named parameters for Page: When instantiating Page objects, use the named parameter for the image URL: Page(index, imageUrl = url) instead of passing an empty string as the second argument (Page(index, "", url)).
  • Throw UnsupportedOperationException: If a source uses an API and doesn't need to parse HTML for images, override imageUrlParse(response: Response) and throw UnsupportedOperationException() instead of returning an empty string. Also use this pattern for unused inherited methods.
  • Cache Regex instances: Define Regex instances at the class level or in a companion object so they aren't recompiled on every method call.
  • Do not hardcode User-Agent: Unless absolutely necessary (e.g., to bypass Cloudflare/protection, or to retrieve a specific mobile layout/different selectors), do not hardcode a specific User-Agent. Calling super.headersBuilder() already provides the app's default User-Agent.
  • Use buildString { }: When building descriptions or dynamic strings, use Kotlin's buildString { ... } instead of manually instantiating a StringBuilder().
  • Media Types: application/json is intrinsically UTF-8. Avoid using application/json; charset=utf-8. Prefer helper functions like toJsonRequestBody() instead of manually specifying media types (e.g., "application/json".toMediaType()).
  • Use getUrlWithoutDomain carefully: It can be useful when parsing target source URLs, but note a current issue with spaces-replace them with URL-encoded characters (e.g., %20).
  • Follow HttpSource workflow: Stick to the general workflow from this base class when possible; deviating may introduce unnecessary complexity.
  • Do not override default HttpSource methods: Avoid overriding methods like mangaDetailsRequest or chapterListRequest if they only replicate the default behavior (GET(baseUrl + manga.url, headers). Only override them if the source requires a different URL structure or custom headers for those specific requests.
  • Configurable sources: By implementing ConfigurableSource, you can add settings backed by SharedPreferences.

Advanced Extension features

Extension logic and app features

  • Mandatory SManga fields: A manga's title and url are mandatory. Do not provide generic fallbacks like "Untitled" or "Unknown" if the site fails to provide a title, as this breaks downloads and library management. Prefer failing loudly (e.g., throwing an exception) so broken selectors are detected early. Silent fallbacks or empty values can hide issues and make debugging harder. If the title or url is missing, it is better to throw or skip the entry entirely.
  • Optional fields: For all other fields, prefer safe calls (?.) and avoid using the non-null assertion (!!). Missing data like thumbnails or descriptions should not crash the entire parsing process. Consider using Kotlin's mapNotNull when parsing lists of elements so that if a single item fails, the rest of the list can still be loaded successfully.
  • When to bump versionId: The versionId property dictates how the app tracks the source. Only override and bump versionId if the source's URL structure fundamentally changes (e.g., old manga URLs no longer work and there is no way to create a redirect). Bumping this forces all users to re-migrate their bookmarks.
  • Self-hosted sources: If you are adding a source for a self-hosted server (e.g., StashApp, Komga, Suwayomi), make your class implement the UnmeteredSource interface. This tells the app not to apply standard rate-limiting to the user's own local server.
  • Preference listeners: When implementing ConfigurableSource, you do not need to manually save values inside setOnPreferenceChangeListener. The Android preference framework saves the value to SharedPreferences automatically.

URL intent filter

Extensions can define a URL pattern so that these URLs can be opened in Mihon.

To do this, you need two files:

  • AndroidManifest.xml which must be placed in the root directory of your extension (Example: src/id/riztranslation/AndroidManifest.xml)
  • UrlActivity.kt which should be placed next to your main file. (Example: src/id/riztranslation/src/eu/kanade/tachiyomi/extension/id/riztranslation/UrlActivity.kt)

AndroidManifest.xml example :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android">

    <application>
        <activity
            android:name=".id.riztranslation.UrlActivity"
            android:excludeFromRecents="true"
            android:exported="true"
            android:theme="@android:style/Theme.NoDisplay">
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />

                <data
                    android:host="riztranslation.pages.dev"
                    android:pathPattern="/..*"
                    android:scheme="https" />
                <data
                    android:host="riztranslation.rf.gd"
                    android:pathPattern="/..*"
                    android:scheme="https" />
            </intent-filter>
        </activity>
    </application>
</manifest>

The AndroidManifest.xml file will contain an android:name attribute that refers to the path of your UrlActivity.kt file. For example, if the extension is Riztranslation, the android:name will be .id.riztranslation.UrlActivity.

Next, you have the <data android:scheme="https" android:host="host" android:pathPattern="/..*" /> element; you can have it multiple times, which allows you to specify the URL that can be opened in Mihon. You can read more about this in Android's <data> documentation.

Now, as for UrlActivity, you can just use the example below.

Caution

The activity does not support any Kotlin Intrinsics specific methods or calls, and using them will cause crashes in the activity. Consider using Java's equivalent methods instead, such as using String's equals() instead of using ==.

You can use Kotlin Intrinsics in the extension source class, this limitation only applies to the activity classes.

To explain how it works, it will trigger Mihon's SEARCH action, passing the URL as a query and specifying that it comes from your extension to narrow down the search. Avoid putting any logic in this file; instead, implement it in your extension's class.

class UrlActivity : Activity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val intentData = intent?.data?.toString()
        if (intentData != null) {
            val mainIntent = Intent().apply {
                action = "eu.kanade.tachiyomi.SEARCH"
                putExtra("query", intentData)
                putExtra("filter", packageName)
            }
            try {
                startActivity(mainIntent)
            } catch (e: Throwable) {
                Log.e("RiztranslationUrl", e.toString())
            }
        } else {
            Log.e("RiztranslationUrl", "could not parse uri from intent $intent")
        }

        finish()
        exitProcess(0)
    }
}

Now all you need to do is adapt the search function (fetchSearchManga) in your extension so that, given a URL, it returns a single manga that matches that URL. For example:

if (query.startsWith("https://")) {
    val url = query.toHttpUrlOrNull()
    if (url != null && url.host == baseUrl.toHttpUrl().host) {
        val typeIndex = url.pathSegments.indexOfFirst { it == "detail" || it == "view" }
        if (typeIndex != -1 && typeIndex + 1 < url.pathSize) {
            val id = url.pathSegments[typeIndex + 1]
            return GET("$apiUrl/Book?select=id,judul,cover&type=not.ilike.*novel*&id=eq.$id", apiHeaders)
        }
    }
}

To test if the URL intent filter is working as expected, you can try opening the website in a browser and navigating to the endpoint that was added as a filter or clicking a hyperlink. Alternatively, you can use the adb command below.

$ adb shell am start -d "<your-link>" -a android.intent.action.VIEW

You can find a complete example of how URLs work in the Riztranslation extension.

Update strategy

In some cases, titles in a source will always have the same chapter list (i.e., they are immutable). These do not need to be included in global app updates. Excluding them saves a lot of network requests and prevents unnecessary load on the source servers. To change the update strategy of a SManga, use the update_strategy field. You can find below a description of the current possible values.

  • UpdateStrategy.ALWAYS_UPDATE: Titles marked as always update will be included in the library update if they aren't excluded by additional restrictions.
  • UpdateStrategy.ONLY_FETCH_ONCE: Titles marked as only fetch once will be automatically skipped during library updates. Useful for cases where the series is previously known to be finished and have only a single chapter, for example.

If not set, it defaults to ALWAYS_UPDATE.

Renaming existing sources

There are some cases where existing sources change their names on the website. To correctly reflect these changes in the extension, you need to explicitly set the id to the same old value, otherwise it will get changed by the new name value and users will be forced to migrate back to the source.

To get the current id value before the name change, you can search the source name in the repository JSON file by looking at the sources attribute of the extension. When you have the id copied, you can override it in the source:

override val id: Long = <the-id>

Then the class name and the name attribute value can be changed. Also don't forget to update the extension name and class name in the individual Gradle file.

Important

The package name needs to be the same (even if it has the old name), otherwise users will not receive the extension update when it gets published in the repository.

The id also needs to be explicitly set to the old value if you're changing the lang attribute.

Note

If the source has also changed their theme you can instead just change the name field in the source class and in the Gradle file. By doing so a new id will be generated and users will be forced to migrate.

Multi-source themes

The lib-multisrc directory houses source code that is useful in situations where multiple source sites use the same site generator tool (usually a CMS) for bootstrapping their website and this makes them similar enough to prompt code reuse through inheritance/composition; which from now on we will use the general theme term to refer to.

Themes are provided as libraries within lib-multisrc. You can apply a theme to an extension by specifying the themePkg property in its build.gradle file.

Creating a new theme

To create a new theme, you need to set up a new module inside the lib-multisrc directory. The structure is similar to a regular extension, but it acts as a base library that other extensions can depend on.

Theme directory structure

$ tree lib-multisrc/<theme_name>/
lib-multisrc/<theme_name>/
├── build.gradle.kts
└── src
    └── main
        └── java
            └── eu
                └── kanade
                    └── tachiyomi
                        └── multisrc
                            └── <theme_name>
                                └── <ThemeName>.kt

<theme_name> should be adapted from the CMS/theme name, and can only contain lowercase ASCII letters and digits. Your theme code must be placed in the package eu.kanade.tachiyomi.multisrc.<theme_name>.

Theme build.gradle.kts

Make sure that your new theme's build.gradle.kts file follows this structure:

plugins {
    id("lib-multisrc")
}

baseVersionCode = 1
Field Description
baseVersionCode The base version code for the theme. This must be a positive integer and incremented whenever a change is made to the theme's implementation that affects the extensions.

Theme main class

The main class of the theme (e.g., <ThemeName>.kt) contains the default implementation for the source sites. It should be declared as an abstract class extending HttpSource, allowing individual extensions to inherit and override its properties and methods.

package eu.kanade.tachiyomi.multisrc.<theme_name>

import eu.kanade.tachiyomi.source.online.HttpSource

abstract class <ThemeName>(
    override val name: String,
    override val baseUrl: String,
    override val lang: String,
) : HttpSource() {
    
    // Theme default implementation...
    
}

Using a Theme

To use a theme in your extension, follow the regular extension creation steps and add the themePkg property to your build.gradle:

ext {
    extName = '<My source name>'
    extClass = '.<MySourceName>'
    themePkg = '<theme_name>'
    overrideVersionCode = 1
    isNsfw = true
}

apply from: "$rootDir/common.gradle"

Notice that instead of extVersionCode, extensions using a theme must use overrideVersionCode. The final extension version code (extVersionCode) is automatically calculated during the build process as theme.baseVersionCode + ext.overrideVersionCode.

Because themes are provided as libraries, your extension's main class will directly inherit from the theme's base class.

Any site-specific overrides, custom functions, or custom icons are implemented directly in your extension's module (src/<lang>/<mysourcename>) by overriding the inherited theme properties and functions.

Running

For local development, use the following run configuration to launch the app directly into the Browse panel.

Copy the following into Launch Flags for the Debug build of Mihon:

-W -S -n app.mihon.dev/eu.kanade.tachiyomi.ui.main.MainActivity -a eu.kanade.tachiyomi.SHOW_CATALOGUES

For other builds, replace app.mihon.dev with the corresponding package IDs:

  • Release build: app.mihon
  • Preview build: app.mihon.debug

If the extension builds and runs successfully, then the code changes should be ready to test in your local app.

Important

If you're deploying to Android 11 or higher, enable the Always install with package manager option in the run configurations. Without this option enabled, you might face issues such as Android Studio running an older version of the extension without the modifications you might have done.

Debugging

Android Debugger

Note

It is generally recommended to rely on logging instead of the Android Debugger. Using standard logs (like Log.d or viewing OkHttp logs) is typically much faster, easier to set up, and is more than sufficient for debugging web scraping logic.

Important

If you didn't build the main app from source with debug enabled and are using a release/beta APK, you need a rooted device. If you are using an emulator instead, make sure you choose a profile without Google Play.

Follow the steps above for building and running locally if you haven't already. Debugging will not work if you did not follow the steps above.

You can leverage the Android Debugger to add breakpoints and step through your extension while debugging.

You cannot simply use Android Studio's Debug 'module.name' -> this will most likely result in an error while launching.

Instead, once you've built and installed your extension on the target device, use Attach Debugger to Android Process to start debugging the app.

Inside the Attach Debugger to Android Process window, once the app is running on your device and Show all processes is checked, you should be able to select app.mihon.dev and press OK.

Logs

You can also elect to simply rely on logs printed from your extension, which show up in the Logcat panel of Android Studio.

Inspecting network calls

One of the easiest ways to inspect network issues (such as HTTP errors 404, 429, no chapter found, etc.) is to use the Logcat panel of Android Studio and filter by the OkHttpClient tag.

To be able to check the calls made by OkHttp, you need to enable verbose logging in the app, which is not enabled by default. To enable it, go to More -> Settings -> Advanced -> Verbose logging. After enabling it, don't forget to restart the app.

Inspecting the Logcat allows you to get a good look at the call flow and is more than enough in most cases where issues occur. However, alternatively, you can also use an external tool like mitm-proxy. For that, refer to the subsequent sections.

On newer Android Studio versions, you can use its built-in Network Inspector inside the App Inspection tool window. This feature provides a nice GUI to inspect the requests made in the app.

To use it, follow the official documentation and select the app's package name in the process list.

Using external network inspecting tools

If you want a deeper look into the network flow, such as inspecting the request and response bodies you can use an external tool like mitm-proxy.

Setup your proxy server

We are going to use mitm-proxy but you can replace it with any other Web Debugger (i.e. Charles, Burp Suite, Fiddler etc). To install and execute, follow the commands below.

# Install the tool.
$ sudo pip3 install mitmproxy
# Execute the web interface and the proxy.
$ mitmweb

Alternatively, you can also use the Docker image:

$ docker run --rm -it -p 8080:8080 \
    -p 127.0.0.1:8081:8081 \
    --web-host 0.0.0.0 \
    mitmproxy/mitmproxy mitmweb

After installing and running, open your browser and navigate to http://127.0.0.1:8081.

OkHttp proxy setup

Since most of the manga sources are going to use HTTPS, we need to disable SSL verification in order to use the web debugger. For that, add this code to inside your source class:

package eu.kanade.tachiyomi.extension.en.mysource

import android.annotation.SuppressLint
import eu.kanade.tachiyomi.source.online.HttpSource
import okhttp3.OkHttpClient
import java.net.InetSocketAddress
import java.net.Proxy
import java.security.SecureRandom
import java.security.cert.X509Certificate
import javax.net.ssl.SSLContext
import javax.net.ssl.TrustManager
import javax.net.ssl.X509TrustManager

class MySource : HttpSource() {
    private fun OkHttpClient.Builder.ignoreAllSSLErrors(): OkHttpClient.Builder {
        val naiveTrustManager = @SuppressLint("CustomX509TrustManager")
        object : X509TrustManager {
            override fun getAcceptedIssuers(): Array<X509Certificate> = emptyArray()
            override fun checkClientTrusted(certs: Array<X509Certificate>, authType: String) = Unit
            override fun checkServerTrusted(certs: Array<X509Certificate>, authType: String) = Unit
        }

        val insecureSocketFactory = SSLContext.getInstance("TLSv1.2").apply {
            val trustAllCerts = arrayOf<TrustManager>(naiveTrustManager)
            init(null, trustAllCerts, SecureRandom())
        }.socketFactory

        sslSocketFactory(insecureSocketFactory, naiveTrustManager)
        hostnameVerifier { _, _ -> true }
        return this
    }

    override val client: OkHttpClient = network.cloudflareClient.newBuilder()
        .ignoreAllSSLErrors()
        .proxy(Proxy(Proxy.Type.HTTP, InetSocketAddress("10.0.2.2", 8080)))
        .build()
}

Note: 10.0.2.2 is usually the address of your loopback interface in the android emulator. If the app tells you that it's unable to connect to 10.0.2.2:8080 you will likely need to change it (the same if you are using hardware device).

If all went well, you should see all requests and responses made by the source in the web interface of mitmweb.

Building

APKs can be created in Android Studio via Build > Build Bundle(s) / APK(s) > Build APK(s) or Build > Generate Signed Bundle / APK.

If for some reason you decide to build the APK from the command line, you can use the following command (because you're doing things differently than expected, I assume you have some knowledge of gradlew and your OS):

// For a single apk, use this command
$ ./gradlew src:<lang>:<source>:assembleDebug

Submitting the changes

When you feel confident about your changes, submit a new Pull Request so your code can be reviewed and merged if it's approved. We encourage following a GitHub Standard Fork & Pull Request Workflow and following the good practices of the workflow, such as not committing directly to main: always create a new branch for your changes.

If you are more comfortable about using Git GUI-based tools, you can refer to this guide about the Git integration inside Android Studio, specifically the "How to Contribute to an to Existing Git Repository in Android Studio" section of the guide.

Important

Make sure you have generated the extension icon using the linked Icon Generator tool in the Tools section. The icon must follow the pattern adopted by all other extensions: a square with rounded corners. Make sure to remove the generated web_hi_res_512.png.

Please do test your changes by compiling it through Android Studio before submitting it. Obvious untested PRs will not be merged, such as ones created with the GitHub web interface. Also make sure to follow the PR checklist available in the PR body field when creating a new PR. As a reference, you can find it below.

Pull Request checklist

  • Updated extVersionCode value in build.gradle for individual extensions
  • Updated overrideVersionCode or baseVersionCode as needed for all multisrc extensions
  • Referenced all related issues in the PR body (e.g. "Closes #xyz")
  • Added the isNsfw = true flag in build.gradle when appropriate
  • Have not changed source names
  • Have explicitly kept the id if a source's name or language were changed
  • Have tested the modifications by compiling and running the extension through Android Studio
  • Have removed web_hi_res_512.png when adding a new extension