are there email login api i can use for my website ?

hello. not sure if this is a good sub to ask this q. i'm currently working on a project. we want to allow users to resume a previous workflow but we don't have *user login pages.

i was thinking we'll allow users to give us their email, we will redirect them to start their workflow. they can leave any time but when they want to resume, we'll ask for their email again, email them a unique link that maps back to their existing workflow, and we will populate the workflow data so users can continue wtvr they are doing on our website.

trying not to build too much if possible. i can see how we can implement this too but if there's product like this available to save some work will be great.

thank you so much !!