There are many. The top 14 are members of the Free File Alliance[0]. There are tens, if not hundreds more that do federal filing. Unfortunately many are cheap clones of TurboTax or re-skinned versions of Drake[1].
Disclosure - I'm the CEO of Common Form[2]. My co-founders and I are all ex-Intuit employees. We currently only cover the 1040EZ, but we're expanding as fast as we can.
I'm surprised there are so many, I would have expected that keeping up with the changes in the tax law would be a pretty expensive barrier to entry, especially given the IRS sometimes isn't totally sure themselves. Although it seems like the vast majority focus only on the 1040EZ which I guess radically simplifies things.