[sareiodata]

I built https://markdownbin.com/ because a friend was complaining something like this doesn't exist.

Nobody uses it and probably that's why it doesn't exist.

[stevekemp]

I created https://markdownshare.com/ for the same purpose; but due to abuse I've retired it.

Shame really, because I liked the service and it was quick/simple to build.

[colecut]

It's funny how building the functionality can take a couple hours but human proofing it is a never ending task

[_-o-_]

It's neat, but probably needs a bit more features for it to be more useful than pastebin.

[RBerenguel]

Well, there's StackEdit [1], and we use it (at work, for an end-of-sprint automated list of finished stuff for the demo)

[1]: https://stackedit.io/

[zgrep]

There is https://txti.es/ . Additionally, GitHub Gists will render markdown.