How to add a local file in JSfiddle?

I prefer https://www.webpackbin.com. It's quite neutral in style, quick to load and you can also use it as anonymous user.

When you saved some code, you can share this code with others by handing over your link. When they now start modifying it, they'll effectively create their own version. Your version will stay the same and is still accessible on the same link.

I don't think that jsfiddle allows you to upload additional html files -- only other resource files. It also assumes working only with one of the four panes (HTML/CSS/JS).

Instead, you can use a site like Plunker which allows you to add different files of arbitrary types. They will link together: http://plnkr.co/edit/NgdBXGkDDG1nOy47TaSK?p=preview

You could use orionhub.org to host your file, link to it from fiddle. On Orion, you'd have to create the project, add file to it, make the file visible to the external world as part of that project. It's a bit convoluted at first, but makes sense and you'll get used to it.

Detailed steps for making certain resource publicly available via Orion:

1. Import/create a file
2. Select View on Site via Open Related menu

3. Add a site (if not exists) and copy the public link from View

UPDATE 2019/06/26 - codesandbox.io seems to allow file upload, but may not allow hotlinking to it. It might be time to move that altogether. (if the circumstances warrant, of course)