Somebody posted in the forum about Fiddler and Postman, and the suggestion was to disable HTTPS.
That's not really a good idea since your authentication data will be unencrypted.
But here's how to do it:
* Enable HTTPS decrypting in Fiddler:
Tools > Options > HTTPS
Enable "Decrypt HTTPS traffic"
Accept all warnings about installing Fiddler's root certificate.
* Export Fiddler's root certificate:
Start > Run; type "certlm.msc"
Go to Certificates - Local Computer > Trusted Root Certification Authorities > Certificates
Right click "DO_NOT_TRUST_FiddlerRoot" and select "All Tasks > Export..."
Select "Base-64 encoded X.509 (.CER)"
Save the file somewhere.
* Enable certificate in Postman:
File > Settings > Certificates
CA Certificates => On
Click "Select File"
Point to your saved certificate file.