Hot on the heels (or is that feathers) of their big 99-cent HD sale, Rovio has decided to make Angry Birds, the best selling app of all time, free for the first time ever. So it's without question that Angry Birds is today's Free App of the Day!

Their official Twitter account has yet to mention the sale, so it appears as though Rovio is keeping quiet about the matter as of now. You're hearing it here first!

But we'll all likely be seeing it soon, as it's almost guaranteed that Apple will feature the sale inside the App Store. In addition to going free for both iPhone and iPad, there's also 15 new levels for the Bad Piggies episode.

Don't get angry, get happy! There's no time to waste here, download yourself a copy of Angry Birds today for your iPhone and iPad!