DuckDB
A small, fast database that runs inside your program instead of on a server, built for everyday analysis of modest amounts of data.
DuckDB is a database you do not have to set up. Most database systems are separate servers you install, configure and connect to. DuckDB runs inside whatever program you are already using, reads files like CSV, JSON and Parquet straight off your disk or from cloud storage, and answers SQL questions about them in a fraction of a second. Installing it takes about as long as installing any other small library.
It exists because the database world spent years optimising for enormous datasets while most real work is much smaller. The great majority of queries people actually run touch a terabyte of data or less, and DuckDB is built specifically for those. That also makes it a natural fit for AI agents, which tend to explore data the way people do: lots of small exploratory questions before they know what they are really looking for.