What is a bid request?

A bid request in programmatic advertising is a data message sent by an app’s ad server or supply-side platform (SSP) when ad space becomes available during an automated auction, also known as real-time bidding (RTB). It contains details about the user, device, and ad placement, so advertisers can decide whether to bid and how much to offer.

In mobile marketing, a bid request is generated when a user initiates an app session with an available ad slot. The app’s ad server or SSP sends this request to an ad exchange, where multiple demand-side platforms (DSPs) can review it. 

Each DSP determines whether the impression opportunity matches its targeting criteria. If it does, the advertiser submits a bid. Then, the exchange selects the highest bid and serves the ad to the user, all within milliseconds.

A bid request includes data, such as:

• Device information (device type, OS, browser)
• Location data (often based on IP address)
• Ad slot details (size, format, placement)
• User identifiers (e.g., IDFA, GAID, or cookies)
• Publisher or app information
• Contextual data (content category or app type)

Not all of this data is always available. Privacy settings or user consent can limit the information shared in a bid request.

Bid requests facilitate real-time, data-driven advertising by allowing each ad impression to be appraised and auctioned independently, rather than relying on generalized placements. For advertisers, bid requests support more efficient and targeted media buying, which can improve campaign performance and return on ad spend (ROAS).

For publishers, bid requests increase competition by enabling multiple advertisers to simultaneously bid for the same impression. This mechanism can maximize revenue and ensure inventory is sold at the best available prices.