Reliable distributed systems need more than competent engineering: they need a robust theoretical foundation. CRDTs, or conflict-free Replicated Data Types, are a set of properties or behaviors, discovered more than invented, which enable a distributed system to achieve consistency without consensus, and sidestep entire classes of problems altogether.

This talk provides a practical introduction to CRDTs, and describes a production CRDT system we built at SoundCloud to serve several product features.