Apex REST API call throws 401 error, status: token expired or invalid

Question

I am trying to call external REST API from Salesforce. Sometimes I get error 401 with messages token expired or token invalid. Is there a way to prevent calling API when token is not valid. The thing is that I have only token as String, I do not have private/public key so I cannot use Crypto.verify() method. I use JWT token for authentication. This issue is also happening in Postman. But, when my token is valid I got 200 code, status OK. Any help?

Answer 1

You cannot do something without having necessary information which requires it to do what you are trying to do. tldr; You cannot decode JWT token without its keys (unless JTW is just signed and not encrypted).

Your best bet (which is safe one) is to catch Invalid Auth error, re-init the session and then call again. If you include this check in lower-layer of your application service stack, one time implementation will handle for many api calls.