GNU dbm (or GDBM, for short) is a library of database functions that use extensible hashing and work similar to the standard UNIX dbm. These routines are provided to a programmer needing to create and manipulate a hashed database.

The basic use of GDBM is to store key/data pairs in a data file. Each key must be unique and each key is paired with only one data item.

The library provides primitives for storing key/data pairs, searching and retrieving the data by its key and deleting a key along with its data. It also support sequential iteration over all key/data pairs in a database.

For compatibility with programs using old UNIX dbm function, the package also provides traditional dbm and ndbm interfaces.

GNU gdbm is written by Philip A. Nelson, Jason Downs and Sergey Poznyakoff.