As of Tuesday, Aerospike's in-memory NoSQL database solution is open source. Boasting impressive performance over NoSQL competitors (though some may not agree), Aerospike's move to open source is promising for any developer looking for new options and opportunities to get involved in the NoSQL space. Aerospike's announcement captures the openness pretty well:
The code for Aerospike clients and the Aerospike server is published on github. Clients are available under the Apache 2 license so you can use and modify with no restrictions. The server is available under AGPL V3 to protect the long term interests of the community – you are free to use it with no restrictions but if you change the server code, then those code changes must be contributed back.
Aerospike Community Edition has no limits on the number of servers, tps or terabytes of data, and is curated by Aerospike. Use is unlimited and the code is open.
There is also a commercial Enterprise Edition as well. If you're interested in some more general background on Aerospike, they've got a bit of a video series going, too - here's a sample: