Why does Google Chrome automatically add www. prefix for some websites but it does not add it for others?

Ok, so I noticed that I have to type the http:// prefix so that I can bypass Chrome’s suggestion engine in comparison with Firefox, where I can type it without the prefix. I think this tricked me into thinking it does this every time, when in fact it doesn’t, it was only my history that appeared as suggestion, and I used the www. variant in the past.

I will close the question as solved.

I had the same issue trying to browse to an internal webpage that's not available to the public internet. Disabling the prediction service didn't cause the "www" to stop being prepended to the domain string. Typing http://... and https//... also didn't help.

In my case it was working fine in incognito mode.

It was only after I cleared my cookie data that it started working again.

  • Settings > Advanced > Privacy > "Clear browsing data..."
  • Check "Cookies and other site and plugin data" (other checkboxes shouldn't be necessary)
  • Click "Clear browsing data"

I'd guess if you have a browser plugin that lets you edit cookies, you could just delete cookies for that site before you try the above if you'd prefer not to wipe ALL of your browser cookie data and log yourself out of everything. In my case it was a relatively new browser install so I didn't mind YOLO-ing it.

To clarify how this answers the OP's question, it's possible for cookie/site data to interfere with the way your URLs are resolved, so if the accepted answer doesn't explain it, this might.