Blackbox Explorer for STorM32 is based on thenickdude's fantastic Cleanflight Blackbox Explorer, here: https://github.com/cleanflight/blackbox-log-viewer. The license is GPLv3.
Follow the Manual Chrome App Install procedure: Download the zip file, and unpack it to somewhere on your computer. Open Google Chrome, click on the menu button, and choose tools -> extensions. Check the developer mode checkbox in the right top corner, hit the load unpacked extension button, and browse to the unpacked folder. This adds the app to the Chrome App Launcher.