Using The Teensy Loader on Mac OS X Update: Teensy 3.0 is supported by Teensyduino. After installation, Teensy Loader is in hardware/tools. It is run automatically when using Verify or Upload within the Arduino software. This version on this web page has not been updated for Teensy 3.0. Please install Teensyduino to use Teensy 3.0. Files to download: Teensy Loader Disk Image (4.4 megabytes, Mac OS