Gistbox is leaving us.
Unfortunately, with our attention focused on Cacher, we will be ramping down GistBox. After a period for user migration, GistBox will enter maintenance mode (no feature updates or sign ups) on October 1st, 2017. GistBox will be inaccessible starting December 1st, 2017. Please contact us if you have questions.
Luckily, I found an open source alternative. It is not a web app, but it is good enough.