To inject the

aud

claim into the JWT generated from a session, you can use the

id_token

mutator in Ory Oathkeeper. This mutator allows you to specify custom claims, like the audience of ID tokens, via the

claims

field of the mutator's

config

field. Here is an example of how you can set the

aud

claim in the configuration:

json {   "handler": "id_token",   "config": {     "claims": "{\"aud\": [\"<https://my-backend-service/some/endpoint\>"],\"def\": \"{{ print .Extra.some.arbitrary.data }}\"}"   } }

In this example, the

aud

claim is set to the URL of the backend service. The

def

claim is set to an arbitrary data from the

Extra

map. The values are parsed by the Go

text/template

package for value substitution, receiving the

AuthenticationSession

struct. Please note that certain keys (such as the

sub

) claim can't be overwritten. For more details, please check the [Ory documentation](https://www.ory.sh/docs/oathkeeper/pipeline/mutator#id_token-claims).