Supplier No Bid Reason

Suppliers can receive two kinds of No Bid Responses (NBRs) from BidSwitch.

  • A Buyer No Bid Response, which is usually an empty 204 response indicates that only one particular Buyer did not bid on the offer. See the Buyer No Bid Response section for an example of this kind of response.

  • A BidSwitch No Bid Reason, which contains the nbr field indicates that the particular Bid Request was not forwarded to any Buyers due to it failing impression anomaly checks.

  • The No Bid Reasons sent by BidSwitch conform with those outlined in the Open RTB Specification, sections 5.22 and 7.1.

A BidSwitch No Bid Reason can occur for a number of different reasons, including suspected fraudulent activity like bot traffic or traffic coming from a known bad actor IP, site/publisher blocking, or invalid request elements. BidSwitch will continue to add more nuanced NBRs as time goes on.

By returning this information to Suppliers, it allows them to address potential problems in their system. If a No Bid Reason is triggered, BidSwitch responds with a HTTP 200 response and one of the following codes in the nbr field depending on what has been identified as the problem.

BidSwitch No Bid Reasons


OpenRTB Description

BidSwitch Usage


Unknown Error

Not used


Technical Error

Not used


Invalid request

Bid requests that are treated as bad by BidSwitch, except for in-app requests with no IFA, which use #8


Known Web Spider

Not used


Suspected non-human traffic

The bid request was identified to be from a bot or other non-human activity


Cloud, Data centre, or Proxy IP

The bid request was blocked because of its IP


Unsupported Device

Not used


Blocked Publisher or Site

The Publisher ID, Site ID, Site Domain, App Domain, App Bundle, or App Name have been blocked in BidSwitch


Unmatched User

In-app bid requests without an IFA. This does not apply to cookie-less website bid requests.


ads.txt validation failed to verify the Supplier as an authorised seller of the publisher’s inventory

Example Response



Enabling No Bid Reason

  • To receive a No Bid Reason, you need to support the nbr field in bid responses.

  • To enable No Bid Reasons on your BidSwitch account, contact