The most common and cost-effective option for identifying is the use of ID badges in different forms and for different reading methods. Most RFID reading methods are used, their specific selection depends on the desired degree of security or other preferences. If necessary, contactless reading methods can be combined with other identification methods such as biometrics or a PIN code or a magnetic stripe codes (hidden or visible - only for ID cards). RFID badges are typically available in credit card format or as a keychain.
We are happy to advise you about concrete alternatives - specific to your requirements!