I thought I'd use my first post on Dev to introduce our project: Eclipse RDF4J, a Java framework for working with RDF knowledge graphs.
First things first: I'd like to invite you to come help us improve it! We're looking for anyone interested in doing some Java coding, but also help us write documentation, and/or improve the web frontend UI or our project website.
Our Github repo contains our code, including the website and documentation. We've tagged some issues with the hacktoberfest or good first issue tags to get new contributors started, though you're most welcome to pick something else as well, of course. We've got a guide for contributors that outlines how to best get going, and of course you can get in touch directly with any questions or comments (we're on gitter and there's a mailinglist, too).
We also have a video explaining what we're about (it's a one hour webinar going into quite some detail):
The "Too long; didn't watch":
RDF4J is a Java framework for working with knowledge graphs expressed as RDF data (if you've never heard of RDF, it's a W3C standard for serializing data as graphs - see our getting started tutorial for a brief introduction).
RDF4J has a suite of parsers and writers for RDF, a query engine for the SPARQL query language, several database implementations, and a set of powerful and flexible Java APIs that make it possible to quickly and easily work with RDF data in Java, including talking to any RDF database or public knowledge graph. For example, many people use it to interact with the Wikidata knowledge base, and connecting their own sources of data with other information to mash up and combine data into very powerful knowledge-driven applications. Bingo!
So anyway, come talk to us, we're a friendly bunch of about 3-5 regular contributors (depending on what you count as "regular") who will be overjoyed to help you get started (and you definitely don't need to be an RDF expert already to start getting involved!).