CodeSandbox is an online editor that helps you create web applications, from prototype to deployment.
I'm Teacher Assistant @Ironhack and I let the students choose between codepen and codesanbox : almost all of them choose Codesandbox :)
In addition, you're able to play around very easily with different frameworks, this is very sweet!
Hard to find
A great tool to quickly get started using a JS framework (or no framework at all). Very useful for teaching, prototyping and issue reproductions!
Very easy to use
In the cloud
No @vue/cli integration yet :D