I have asked a lot if I have steam id API or how I did Steam ID Finder, so I decided to make article so I can link them here instead of typing all the stuff.
I don't provide any steam API as Valve provides everything you need and more.
Here the links you will need:
- How to deal with Steam_0:1:12345678 format: https://developer.valvesoftware.com/wiki/SteamID
- How to deal with steam vanity url: https://wiki.teamfortress.com/wiki/WebAPI/ResolveVanityURL
- Getting steam id details: https://developer.valvesoftware.com/wiki/Steam_Web_API#GetPlayerSummaries_.28v0002.29
^This will cover everything you need to grab it by yourself. Read it carefully and if you have some additions to this write comment.