HTTP Headers

Media Owners
Last Updated: February 12, 2026•

The Index OpenRTB bidding API uses the HTTP 1.1 protocol and sends the following request headers.

Note: Avoid using HTTP 1.1 Expect header with "100-continue". At this time, Index does not support the behavior accompanying the "100-continue" expectation. Assuming that the request body meets the Index maximum Content-Length header requirements, the request will succeed. An HTTP error code 417(Expectation Failed) is returned if the "100-continue" expectation is received.

AttributeScopeDescription

Connection

Optional

The connection type for the request. Index accepts "Keep-Alive" (recommended) or close.

Content-Length

Required

The length of the request body.

Content-Type

Required

The content type for the request. This value is always"application/json".

Host

Required

The domain of the bidding URL.

x-openrtb-version

Optional

The version of the OpenRTB protocol used for the request. Index supports versions up to "2.6".

Note: While we accept up to "2.6" as the value, Index currently only supports the functionality associated with a subset of OpenRTB 2.6 fields, as documented in our List of supported OpenRTB bid request fields for sellers. Support for additional fields is ongoing. For more information on supported OpenRTB 2.6 fields as they are released, see our Release Notes.

Content-Encoding: gzip

Optional

Specifies that the payload in the request body utilizes gzip compression. For more information about gzip, see Send and receive compressed traffic using gzip.

Accept-Encoding: gzip

Optional

Specifies that you accept gzip compression and want to receive gzip compressed bid responses from Index. For more information about gzip, see Send and receive compressed traffic using gzip.

No-bid signal

To express a "no-bid", Index will send an empty response with HTTP Status Code 204 "No Content".