Nexus is a Repository Manager for Maven, NuGet and other binary artifact repositories. Repository managers serve two purposes: they act as highly configurable proxies between your organization and the public repositories and they also provide an organization with a deployment destination for your internally generated artifacts.
Nexus is an open source repository manager for Maven and other repository formats like P2, NuGet, static sites, RPM/YUM, NPM, NuGet, RubyGems and more. Repository managers serve two purposes: they act as highly configurable proxies between your organization and the public repositories and they provide an organization with a deployment destination for your internally generated artifacts.
The true power of Nexus comes into play with its caching mechanism i.e its ability to cache any component from any source. On first request, nexus scans its storage to see if the requested component is present in the storage location or not. In case the particular artifact is not present, it will fetch the artifact from a list of configured remote repositories and place it in its storage location before serving the requester. Next time the same component is requested, it will be served directly from the storage, thus saving the overhead of fetching it from the remote repository.
In addition Nexus provides a user interface around the administrative and user related tasks such a searching components and provides further features like support for release process, control over available artifacts, audit and security controls. Nexus Professional also displays up-to-date information about known security vulnerabilities and license issues.
Nexus improves build times as described in this video presentation which provides an overview of how a local Nexus server, that you set up and manage, caches artifacts that are downloaded from the Central Repository (aka Maven Central) and other repositories. There is a commercial version, Nexus Professional, with more features available. You can find out more about it all on the dedicated user community website with lots of helpful blog posts, videos and more.
