• No installation.
• No server needed. It works offline.
• No building process needed. Built-in Babel support. It translates your code at runtime.
• Supports external libraries and styles. Like React for example.
• Export your work to an external file
• Supports import statement (between the files of app)
• Supports importing of CSS and HTML files
• Supports dependencies via HTTP (everything from unpkg or cdnjs)

https://poet.krasimir.now.sh/new

• Online at poet.krasimir.now.sh
• Offline by downloading Demoit.zip

When you open the app and start writing code you progress gets saved to an internal state. You can grab it by opening the bar at the top and clicking on the gear icon (check the "Export" section). The JSON there contains all the configuration that Demoit needs. You can save this configuration to an external file and let Demoit knows the path to it via the state GET parameter (for example http://localhost/demoit?state=./mycode.json).

• ?state=<path to json file> - relative path to a JSON file
• ?mode=preview - it loads the editor just in a preview mode. The code is visible but not compiled, not editable and not executed. This significantly reduces the file size and it is useful for showing your code in a blog post for example.
• ?mode=readonly - it loads the editor in a readonly mode. It means that the code is transpiled and executed but you can't make changes. This also reduces the page's size because it is not loading Babel and CodeMirror (which is roughly 1.5MB)

• You have to download Demoit.zip
• You need to transfer your progress to a JSON file and pass it to the app via state GET param
• If you use external dependencies make sure that they are also saved locally and the path to the files is properly set (check the gear icon in the status bar at the top of the app)

• Ctrl S / Cmd S - essential for seeing the result of your code. This keys combination triggers transpilation and execution.
• Ctrl <0-9> / Cmd <0-9> - switch between files

Right mouse click on the file's tab.

It means that the browser doesn't load the files that the tool needs because the protocol is file://. That's a problem in Chrome at the moment. Everything works fine in Firefox. To fix the problem in Chrome you have to run it like so:

open /Applications/Google\ Chrome.app/ --args --disable-web-security

or under Windows:

chrome.exe --disable-web-security

Of course Demoit works just fine if you open index.html via http protocol but to do that you need a server.