Is Cassandra free?
Yes, Apache Cassandra is free and open source. Apache 2.0 license. Commercial support available from DataStax.
What is Cassandra?
Cassandra is a distributed NoSQL database. High availability, no single point of failure. Used by Netflix, Apple, and more.
Cassandra vs MongoDB?
Cassandra excels at write-heavy workloads. MongoDB is more flexible for queries. Cassandra for scale; MongoDB for flexibility.
When should I use Cassandra?
High write throughput, global distribution, always-on requirements. Time-series data, IoT, messaging. Not for complex queries.