Help with NTLM Authentication

I’m using native app latest version 6.0.10 and getting 401 - Unauthorized: Access is denied due to invalid credentials while trying to test our WebAPI endpoints hosted in an IIS 7.5 server. For Authorization type, I have selected NTLM Authentication and supplied the Windows username and password.

Is the NTLM Authentication broken in version 6.0.10? If so how can I install a lower version that supports it?

Can you share the response headers from postman-console?

Here’s the response headers, thanks for looking:

Response Headers:
date:“Thu, 26 Apr 2018 19:40:17 GMT”

That seems to be alright. I tested on an IIS server which is sending the exact same header and it’s working for me.
Can you try the same credentials by opening the URL in a browser window? Does that work?

Also, if possible share following information (either here or mail us at

  • num of requests that you see in postman-console (3 or 4)
  • complete raw log of each request (see below example screenshot)

The same URL works on a browser window and it downloads the API response as a JSON file.

There are 3 requests that goes out in the Postman console (attached).
Also attached are the RAW log of each of the 3 requests.

RAW log Request 1

RAW Log request 2

PRETTY log Request 2

RAW Log Request 3

Did this issue ever get resolved? I’m having similar NTLM issues but it seems these threads usually go dead without solution. Any info you can provide would be most helpful.

I am having the same issue with a much newer version of Postman.

Version 7.26.1
win32 10.0.18363 / x64

My request works fine in the browser (Edge + Chrome) and works without issue in Insomnia. I don’t really want to switch to Insomnia but at least it seems to be working using that tool.