I haven't tried repl.it, but the ace editor (which cloud9 uses) doesn't support the arrow keys on the external keyboard for iOS which is a deal breaker for me.[1]

Code Sandbox [2] however allows you to select which editor (Monaco or CodeMirror) and CodeMirror has a fix for handling the arrow keys. I've found Code Sandbox works pretty well on my iPad - it has a nice Github integration so I can commit directly or open pull requests from the web IDE.

[1]: https://github.com/ajaxorg/ace/pull/3172 [2]: https://codesandbox.io

I found cloud9 a bit annoying to use. It basically spins up an EC2 instance for you that you are then connecting to, so you have pretty much a full file system which was cool, but it felt like they were really pushing Lambda as the way to go. Trying to run a bunch of dockerized microservices on a single instance (which is what our infrastructure is) was possible, but it just felt like an uphill battle, so I abandoned it.

Repl.it was much easier to work with, IMO. The problem I ran into was that it worked well for small projects or prototyping, but became a pain if I had to switch between multiple projects regularly.

IMO, both were cool and overall fairly solid, but there were just too many little annoyances that piled up that I don't get with my current local development set up. It just felt like I spent a lot of my time configuring things or trying to hack things to fit my workflow.

That all being said, I'm not the most patient person with new tools and this was a while ago, things might have changed or may fit your development style better. I'd say they are worth at least looking into.