File API Input Layer (FAIL) is a template-of-sorts for building one-off tools that require the user to upload files and then have the app do something amazing with the aforementioned files. Like cssshrink.com or similar.

http://phpied.com/fail for more info.

https://phpied.com/files/fail for a demo.

To create a new React app project using FAIL as a template, do

$ craft MyApp https://github.com/stoyan/fail/archive/master.zip

(see https://github.com/stoyan/craft if the above command makes no sense)