Apache Celix is an open-source implementation of the OSGi specification adapted to C and C++ developed by the Apache Software Foundation. The project aims to provide a framework to develop (dynamic) modular software applications using component and/or service-oriented programming.

Apache Celix is primarily developed in C and adds an additional abstraction, in the form of a library, to support for C++.

Modularity in Apache Celix is achieved by supporting - run-time installed - bundles. Bundles are zip files and can contain software modules in the form of shared libraries. Modules can provide and request dynamic services, for and from other modules, by interacting with a provided bundle context. Services in Apache Celix are "plain old" structs with function pointers or "plain old C++ Objects" (POCO).