No one needs to ever use an open source database. With Informix you can get a free download, and the best User group to help you use and support it. The new out of the box configurations for version 12.10+ start up your instance with an excellent start up configuration.
Informix Developer’s Edition is a fully functioning Informix database for the purpose of developing new systems. The DE version is realized for every new fix pack version of Informix.
Informix Innovator C is a scaled down version of the Informix Engine with the primary database functionality but without many of the advanced features like replication. It is allowed to be used for any life cycle, development or production.
For more information on the Informix Family of products.