I need to build a simple (almost) frontend only website (HTML, CSS, JS) and host it on Amazon S3. But I also need to store contact details of people who fill out the form. The only way I have ever handled this type of scenario is the usual way, i.e. by sending the data to the server and handling the CRUD operations on the server side.

But in the current situation, I think that firing up a server (an EC2 instance) will be an overkill (as well as expensive). Is there any way by which I can directly store data submitted by user to the DB? (SQL, NoSQL anything would do).

The closest I got to the Solution is DynamoDB Low-Level API which I have not run but I think that making REST call from the html page would do the trick BUT the problem is that it would expose the Authorization Credentials.

Is there any way I can either use DynamoDB Low-Level API without exposing the credentials? or is there a better solution than using DynamoDB?