I was very surprised to find out how easy this was. Cudos to Tink for creating an amazing developer experience!
- Display the UI
https://oauth.tink.com/0.4/authorize/?client_id=<insert client_id here>&redirect_uri=http://localhost:3000/callback&market=SE&locale=en_US&scope=accounts:read,user:read,credentials:read,transactions:read,investments:read,statistics:read
- Get the code in the final url: Code: