As surapaneni rightfully commented - they do offer a free plan for personal use, which you'll be able to use.

I'm using them for some commercial projects just as a client side library to allow uploading files to my s3 account (although they do some work on their server side as well). It's a shame they're changing the terms for the existing user. I don't expect things to be free - unless they are offered as such, with no expiration date.