Probe exactly what PostMan has send in GET request

I’m new to REST APIs. I’ve been using Postman to test an Amazon AWS endpoint written by another provider, quite successfully. This mean I’ve included the AWS authorization credentials, headers, query parameters etc. and get the expected response.
I now need to recreate this GET request in software. My code appears to create the correct hashes and signed message content, but when I send it to the endpoint I get an AWS error telling me the signatures don’t match.
For me to know which part of my code is wrong, I’d like to be able to look at exactly what Postman sent out over the network so that I can compare it to my own code’s output. Is it possible to probe the Postman output?

If it helps, I’m coding in LabVIEW using the HTTPClient library.

You can open the Postman console to see what Postman sends over the network.