Dexmaker is a set of libraries that enable runtime bytecode generation and mocking on Android, primarily to support Mockito test frameworks. It provides two mocking modes: a proxy-based approach (dexmaker-mockito) that generates subclasses via the Dalvik bytecode generation API, and an inline approach (dexmaker-mockito-inline) that uses a JVMTI agent to transform class bytecode at runtime, allowing mocking of final and static methods. The core module (dexmaker) offers a low-level, fluent API for constructing DEX files programmatically, including types, methods, fields, and bytecode instructions. This is complemented by a C++ library (slicer) that reads, writes, and instruments DEX files, used by the inline mock maker to inject hooks into methods. The project is deeply integrated with Android internals, using hidden APIs and native agents, and is actively maintained to keep up with Android platform changes. It serves as the primary mocking solution for Android instrumentation tests where Java bytecode-based mocks (like ByteBuddy) are not available.