I'm trying to understand how NFC works in terms of the interaction between a phone, reader and tag, as I'm about to start developing a .NET Core application for logging people in and out of a building.

Ideally, a user would tap a phone on a reader, this would initiate an api call and log the tap in the database.

From what I understand though, this approach would need an app on the phone in order to transmit the identifying data, it doesn't work with the phones NFC capability alone.

An alternative could be an NFC tag/sticker per user, pre configured with a unique id which could be read by a reader the logged.

Am I on the right path here or is there a better 'standard' approach to do this?

For clarity, I don't require any advice on the .NET side of things, I only mentioned that to give a fuller picture of what I'm planning.