Solution 1:

Merriam-Webster's entry for 'URL' agrees with you. So do those at Oxforddictionaries.com, Cambridgedictionaries.com and Macmillandictionary.com. Netlingo is agnostic, giving both pronunciations.

(That's not to say that the pronunciation 'earl' is wrong, but on a cursory look at the evidence it does seem to be less prevalent than the one which spells out the initials.)

I'm not aware that non-techies and those who work with computers in a professional capacity pronounce the term differently.

Solution 2:

It's not scientific, but the Google Ngram of "a URL" (blue line) versus "an URL" (red line) for the period 1990–2008 suggests that the published works contained in the Google Books database favor the initialism pronunciation over the acronym pronunciation by a substantial margin:

By way of contrast, consider the Ngram chart for "a FAQ" (blue line) versus "an FAQ" (red line) for the same period (note, however, that the magnification of the Y-axis in the FAQ chart is about twice that in the URL chart):

This is consistent with my memory of preferences at the computer and technology magazines where I worked as a copy editor for two decades: without much effort, you could stir up an argument about whether "a FAQ" or "an FAQ" was preferable; but partisans of "an URL" were hard to find.

Solution 3:

I have just watched 30 short videos from YouGlish: https://youglish.com/. 28 people pronounce URl as you -are -ell while 2 people pronounce it as earl.

Solution 4:

In the south of the US, earl is what you put in your car's engine.