OpenNMS is the world's first enterprise grade network management application platform developed under the open source model.
Well, what does that mean?
The OpenNMS Project was started in July of 1999 and registered on SourceForge in March of 2000. It has years of experience on the alternatives.
It was designed from "day one" to monitor tens of thousands to ultimately unlimited devices with a single instance. It brings the power, scalability and flexibility that enterprises and carriers demand.
While OpenNMS is useful "out of the box," it is designed to be highly customizable to create an unique and integrated management solution.
OpenNMS is 100% Free and Open Source software, with no license fees, software subscriptions or special "enterprise" versions.
Contributing to OpenNMS
Before making a pull request, please submit an OCA for copyright assignment. Note that this does not mean that you are giving up your copyright of your changes to OpenNMS, it instead allows for dual copyright over contributed code.
Also, it is recommended that you make your changes in master and make a pull request there, not in one of the release (eg. 1.12 or 1.10) branches. Fixes can be cherry-picked back to a stable branch, but we try to keep churn out of the stable releases if possible.
If you are using Eclipse, please read the Eclipse page for details on setting up your workspace for code conventions and the plugins we use.