It looks like a lot of people are really keen for a free Domino's pizza.
Domino's Free Pizza page is currently experiencing the dreaded "technical difficulties" - presumably due to the large number of people clicking at the same time. We've reached out to Domino's and will update this post as soon as we hear back.
Update: Domino's just sent us the following statement:
Domino’s 10,001 free pizza giveaway promotional tab can be viewed on a desktop and not on mobile.
As anticipated, there is incredibly large demand and we encourage pizza lovers to please be patient.
Domino's claims there is still "thousands" of free pizzas available. If you really, really want that free pizza, try again in a few minutes. (But don't wait too long or you run the risk of missing out.)