Instancio

Instancio is a Java library that automatically creates and populates objects for unit tests. Instead of writing setup code that sets each field by hand, a single call such as Instancio.create(Person.class) returns a fully populated object, including nested objects and collections.

Objects are filled with random data that can be reproduced when a test fails. Instancio can also create lists and streams of objects, and the generated values can be customised for the needs of a test.

Instancio is distributed under the Apache License 2.0 and actively developed on GitHub; version 6.1.0 was released in September 2026.