Welcome to Clearwater

Project Clearwater is an open-source IMS core, developed by Metaswitch Networks and released under the GNU GPLv3. You can find more information about it on our website.

Latest Release

The latest release of Clearwater is “Zamîn”.


Clearwater is architected from the ground up to be fully horizontally scalable, modular and to support running in virtualized environments. See our Clearwater Architecture page for a bird’s eye view of a Clearwater deployment and a guided tour of the various functional components that comprise it.

Looking Deeper

To look at the optional extra features and function of your Clearwater deployment and for discussions about Clearwater scaling and redundancy, see Exploring Clearwater.

Getting Source Code

All the source code is on GitHub, in the following repositories (and their submodules).

  • chef - Chef recipes for Clearwater deployment
  • clearwater-infrastructure - General infrastructure for Clearwater deployments
  • clearwater-logging - Logging infrastructure for Clearwater deployments
  • clearwater-live-test - Live test for Clearwater deployments
  • clearwater-readthedocs - This documentation repository
  • crest - RESTful HTTP service built on Cassandra - provides Homer (the Clearwater XDMS) and Homestead-prov (the Clearwater provisioning backend)
  • ellis - Clearwater provisioning server
  • sprout - Sprout and Bono, the Clearwater SIP router and edge proxy
  • homestead - Homestead, the Clearwater HSS-cache.
  • ralf - Ralf, the Clearwater CTF.


You can contribute by making a GitHub pull request. See our documented Pull request process.

If you want to contribute specifically to this documentation (e.g. to fix a typo or document a missing option), the Markdown files for it are at https://github.com/Metaswitch/clearwater-readthedocs.

There is more information about contributing to Project Clearwater on the community page of our project website.


If you want help, or want to help others by making Clearwater better, see the Support page.

License and Acknowledgements

Clearwater’s license is documented in LICENSE.txt.

It uses other open-source components as acknowledged in README.txt.