How setup header in Postman for Api Gateway authenticated with Cognito?

You have to manually set 'x-amz-security-token' in Postman and pass the token in that header.

Please try this for postman:

http://docs.aws.amazon.com/apigateway/latest/developerguide/how-to-use-postman-to-call-api.html

you choose the AWS Signature option in the Authorization drop-down, and fill out the fields using the key and secret, click update. Postman will sign the request for you.

And also make sure the role being assigned to your cognito users has access to invoke apig.

JoshuaC and Vijayanath Viswanathan thank you both. Following your suggestion I resolved the issue.

I did the follow steps:

1. Setup AWS Signature and click on "Update Request"

2. Add in header "X-Amz-Security-Token" with SessionToken