Iridium started life as CoolStorage.NET way back in 2004 as a personal project to replace LLBLGen, which was a great ORM at the time but was based on inefficient code generation. As the CoolStorage project grew, it was decided to make it open source. At first the ORM was only targeted at Windows .NET applications (server and desktop) but when MonoTouch (later Xamarin) launched its mobile .NET framework for iOS and (later) Android, CoolStorage was adapted to work on mobile platforms as well. Several developers contributed to the project over the years and was used in thousands of projects. It was featured in several books about MonoTouch/Xamarin.

CoolStorage was inspired by ActiveRecord, which meant that it required a base class for every mapped table. In 2013 the library was rewritten from scratch to support POCO class mapping and to make it compatible with every possible database backend and target platform. The new project was named Velox.DB but was ultimately renamed to Iridium.