I have a JWT that uses “sub” attribute as a client identification, after validating it on the gateway everything is fine and the request achieves the API. However, I don’t want to validate the authorization header internally again. I would like to know if is possible to forward the sub data into the header as another parameter.
Yes this is possible. You need to enable context variables and then perform a header transform.
https://tyk.io/docs/transform-traffic/request-headers/#injecting-context-variables-into-headers