How to get AWS access credentials by having users login through a web browser

[jianzs]

I'm working on a tool that helps users manage their AWS resources on their own computers. Before the tool can start handling the users' resources, it needs to get hold of their AWS access credentials. Is there a way I can walk them through a login process using a web browser to obtain these credentials?

I'd rather not use the AWS CLI so that we can keep the steps needed for using this tool to a minimum.

I've learned a few methods, like AssumeRole. It seems that I need to log in to my account first. However, it's not possible to log in to my account on the users' machine.