Does about:blank work in all browsers?

One thing to be aware of is that if you are running a website in https, you need to be careful about blanking out an iframe. about:blank is a non-secure page and so the browser will throw an error to the user that there are non-secure sections of the page if you have an iframe sourced to about:blank.

(Not exactly an answer to your question, but I thought it was worth mentioning)

It's a requirement for HTML5 implementations to support about:blank. Also, about:blank is defined by RFC 6694.

As for non-HTML5 web browsers, it depends. WorldWideWeb, Lynx, and some other browsers don't support about:blank – it wasn't a standard then. The about:blank itself initially appeared in Netscape Navigator 1. Internet Explorer copied that feature from Netscape, and other browsers copied it as well. If the browser supports frames, you can be almost sure it supports about:blank. Otherwise websites using frames with about:blank location created when Netscape was popular would show errors (or not show them, and effectively do what you wanted).

Yes, it works in the following browsers:

Mozilla Firefox

Opera

Internet Explorer

Konqueror

Safari

Google Chrome

MSN Explorer