I am very satisfied by their service, for an avid scientific reader it is invaluable. Not only the output is good (it's mostly right, only slightly more verbose

I am very satisfied by their service, for an avid scientific reader it is invaluable. Not only the output is good (it's mostly right, only slightly more verbose than necessary, for example a^2 will be returned as a^{2}), but also the UX is excellent. The only perk is that they significantly downsized their free tier some time ago. I think there are some papers with open source deep learning models for this task but I never got to try one of them, unfortunately.