How Index counts impressions

DSPs
Last Updated: April 30, 2026•

Note: Index supports billing notifications via burl for all formats and creativeClosed A digital ad made available in various creative types, defined by their size in pixels such as 300x250px. types.

When a DSPClosed Demand-Side Platform (DSP). A software platform that automates bidding decisions in real-time and efficiently connects buyers and audiences through an ad exchange or SSP. Also known as a buy-side platform. wins an auction, Index Exchange (Index) stores the billing notification URL (burl), which is to be sent when a billable event has occurred. Based on the ad formatClosed The format of the ad space on the publisher's site. Banner and video are kinds of ad formats., Index counts a billable event and sends the DSP burl when the billing notification from the Media Owner meets the following criteria:

FormatImpression counting criteria

Web banner

Index expects to receive the billing notification in the adm field within the time to live (TTL) of 600 seconds.

Note: You will receive the billing notification from Index as soon as we receive it from the Media Owner, up to the TTL.

Mobile app banner

  • If you use burl:

    • And the Media Owner supports OMID, Index will send our impression notification and your burl at the same time, when at least one pixel of the banner is painted into the device's viewport.

    • And the Media Owner does not support OMID, but does support burl, both you and Index will receive burl-based impression notifications at the same time. Index puts our impression tracker in the bid.burl to the publisherClosed The owner of a website or app where advertisements are served., which then redirects to your burl.

    • And the Media Owner does not support OMID or burl, your burl will be placed in the ad markup (adm), and both you and Index will receive burl-based impression notification at the same time.

  • If you do not use burl, Index assumes that your impression tracking URL is in the adm that you return. We will still attempt to use OMID, if supported, but we will not use burl for impression counting.

Note: Index uses a TTL of 600 seconds for adm-based impression notifications from Media Owners, and a TTL of three hours for OMID and burl-based impression notifications.

Video (instreamClosed A video ad that displays before (pre-roll), during (mid-roll), or after (post-roll) video content that the user is consuming. The video ad plays within video content, similar to watching TV with commercials. and outstreamClosed An ad placement where the video is not the focal point of the screen and plays with sound-off by default. They can display before, between, or after text, or accompanying streaming content (pre-roll, mid-roll, and post-roll ads), as an interstitial ad, or display as a standalone ad such as slideshows or native feeds.) on web, mobile app, and STVClosed Streaming TV (STV). Video content that is shown across any device with an internet connection, for example a Connected TV (CTV).

Index expects to receive the billing notification from our VASTClosed Video ad-serving template (VAST). A communication standard between ad servers and video players in XML-format that describes the video player's expected behavior. adm within the TTL of:

  • One hour for video (instream and outstream) on web.

  • Three hours for mobile app and STV.

Note: You will receive the billing notification from Index as soon as we receive it from the Media Owner, up to the TTL.

Native on web and mobile app

Index expects to receive the billing notification in the imptrackers[] array or eventtrackers[] array in the native adm within the TTL of 300 seconds.

Note: You will receive the billing notification from Index as soon as we receive it from the Media Owner, up to the TTL.

Index does not count impressions in the following situations: