I am developing a mobile application with React Native , nodejs (express), mongodb. In my app, users register with their phone number and they will receive sms verification code. I am trying to use AWS 3 service (like cognito )but I am new for that. I tried but it has a lot of document. If anyone has an experience on it, can you share me how to apply it in my app? Or can you suggest me any other service or api rather than AWS that compatible to my app functionality?