I came across the quite awesome glot.io last night - it's a kind of pastebin/gist store, except snippets can be executed as code in a number of languages. I can see this being a really useful tool for showing or teaching programming.
There are some pretty great aspects:
- It runs code server-side, so no need to install tools locally. This is useful for quickly demonstrating concepts in other languages. Code runs inside docker containers, for a limited period of time and without network access, but that's enough for most practical purposes.
- It has an API
- It's open source
- Snippets are embeddable, remain executable, and editable! e.g. see below, and try running and changing it too: