For running some tests against the GDAX/Coinbase Pro API, I needed to send properly signed requests with Postman. To achieve this, I’ve created the short pre-request script below that you can easily add to your Postman collection. More information about signing Coinbase Pro API messages can be found in their documentation.
You might want to adapt the variable names and URL path regex according to your needs. Also, don’t forget that you still need to set the proper headers in your request resource. The code below obviously also works outside Postman.