IC: Urban Arcana
Urban Arcana is based on 3.5, not 3.0, but there are a handful of differences between 3.5 and d20 Modern regardless. The MSRD can be found online, and it's serviceable for play, if not ideal.
Edit: More specifically, d20 Modern was rolled out before 3.5, but the ruleset advertised rules designed for the "new version of Dungeons and Dragons" that were released a bit later.
This message was last edited by the user at 16:45, Mon 12 July 2021.