BRN is a file extension used by files created with BrainStorm, a Windows mind mapping application. BRN files can be used after purchasing and activating BrainStorm license, which costs 40 USD.

BRN files store ideas in a structured manner with central main idea and related concepts and alternatives branching from the main line to create a multilevel data tree structure that can be viewed from multiple perspectives. BrainStorm also offers a module that allows users to export data to HTML documents. BrainStorm in now discontinued.