There are many projects, viewers, tools, and libraries based on MuPDF. The following diagram shows the official projects developed by Artifex.

iOS App Kit example
Android App Kit example
mupdf-android-mini App
mupdf-android-viewer App
iOS App Kit
Android App Kit
mupdf-android-mini lib
mupdf-android-viewer lib
Java Viewer
MuPDF Android Library
Python Bindings
WASM Viewer
Java Bindings
C++ Bindings
mutool run
mutool draw
mutool clean
mutool convert
mutool extract
mutool merge
mutool info
mutool pages
mutool poster
Core MuPDF
MuPDF Android Library
iOS App Kit
Android App Kit
mupdf-android-mini
mupdf-android-viewer
libmupdf
The C library that is the foundation for everything MuPDF.
mupdf-gl
The viewer application for Linux and Windows.
mupdf-x11
The original viewer application for Linux and Windows.
mutool
The command line tool suite.
Java Bindings
The JNI bindings and Java classes that expose a low-level Java API to the MuPDF library.
Java Desktop Example
A simple viewer application written in Java. It runs on Mac, Linux, and Windows.
WASM Library
A WebAssembly library and simple high-level API.
WASM Viewer
A single HTML page web application using the WASM library to display PDF files in the browser.
mupdf-android-fitz
An Android library that provides the Java bindings for use with Android apps.
mupdf-android-mini lib and app
The "MuPDF mini" app that is on Google Play. This basic viewer is designed to be a tutorial and example for how to create an Android app from scratch using the MuPDF library. It can also be used as-is to provide an Activity that can be used to display PDF files in other Android apps.
mupdf-android-viewer lib and app
The "MuPDF viewer" app that is on Google Play. This viewer has a more polished UI, but as a result is a lot more complicated and difficult to customize and learn from.
MuPDF App Kit
A full featured software development kit and example app for Android & iOS.