Hello DanielH547,
Thank you for reaching out to Constant Contact API Developer Support.
The Access Token Information endpoint is only compatible with old uncopied keys that still use our old authorization management service, and will not work with the new JWT access tokens. As of March 31, 2022, this POST method is being depreciated. To view the scopes associated with an access token, parse the access token (JWT) claims.
If you're unfamiliar with parsing JWTs, I'd suggest looking for a standalone JWT decoder tool or doing it in code. There are many free JWT decoders available online. If doing it in code, the OpenID Foundation maintains a list of libraries implementing JWT and JOSE specs, which may be a good starting point. Their list can be found here: https://openid.net/developers/jwt/
Please have a look and let us know if you have any other questions!
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