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NTLM (NT LAN Manager) is a Microsoft authentication protocol used for Windows-based systems. Its challenge-response authentication mechanism is primarily used for:
  • SharePoint
  • Exchange
  • Internal corporate APIs
Unlike basic authentication, which has a less secure protection layer, NTLM has multiple handshake steps and offers more robust security.

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NTLM in Bruno

Follow these steps to use NTLM authentication:
  1. Open your request
  2. Navigate to the Auth tab
  3. Select NTLM from the dropdown list
  4. Fill in the required fields:
    • Username: Your Windows username
    • Password: Your Windows password
    • Domain: Your Windows domain name
ntlm-auth

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How Bruno handles NTLM requests

NTLM requests run through Bruno’s standard request pipeline. Your TLS settings, custom CA certificates, client certificates, and proxy configuration all apply to NTLM requests, and the full handshake is visible in the Timeline tab. Because NTLM authenticates the connection rather than the individual request, Bruno keeps the entire handshake on a single connection.

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Redirect behavior

When a server redirects an NTLM-authenticated request:
  • Same origin: Bruno renegotiates the NTLM handshake on the new connection and follows the redirect.
  • Different host: Bruno follows the redirect without authenticating, so the response is the target’s 401 challenge. To renegotiate NTLM with the other host, enable the request’s forwardAuthorizationHeader setting.