The .tk domain is one of those free ones, but it has a nasty habit of breaking when you least expect it. I think TyrOvC said it got falsely reported as spam or something.
Got taken down for a "copyright" violation and contesting it failed. (Guessing it was actually because it got too popular and the registry took it back to profit off of an ad filled landing page :/ )
If I could go back in time and drill "you get what you pay for" into my past self to prevent the link breakage I would.