What does HackerNews think of tiosetup?
Provides setup scripts and instructions for Try It Online
> https://tryitonline.net is a web site that started out as a place for hosting solutions to code golf puzzles presented on http://codegolf.stackexchange.com/. It can be used by anyone for free to quickly try out and share code snippets, with or without code golf in mind alike, in a big number of practical and recreational programming languages.
glot.io[2] is another, which seems to fit more in the realm of "pastebin with runnable snippets".
As I understand it, a big sell of repl.it is that they have some kind of collaborative editing support, which none of the alternatives I was able to find in a few minutes of digging have. Google Colab has this, but only support Python (AFAIK) and is not open source.
1 - https://github.com/TryItOnline/tiosetup
2 - https://glot.io/