What is OpenRTB?

OpenRTB (Open Real-Time Bidding) is the IAB standard protocol for programmatic ad auctions. It defines the JSON-based bid request and response format that DSPs (Demand-Side Platforms), SSPs (Supply-Side Platforms), and ad exchanges use to transact ad inventory in real-time, typically within 100 milliseconds.

OpenRTB Versions

  • OpenRTB 2.3: First widely adopted version, basic banner/video support
  • OpenRTB 2.5: Current standard — added audio ads, native ads, and improved video fields
  • OpenRTB 2.6: Added Pod auction for video ad pods, improved object model
  • OpenRTB 3.0: Next-gen framework with enhanced transparency and security

Required Bid Request Fields

Every valid OpenRTB bid request must include:

  • id — unique request ID
  • imp — array of impression objects
  • At least one impression with an ad type (banner, video, audio, or native)
  • site or app — publisher context (one is required)

Recommended Fields

  • device — device info (UA, IP, OS) for targeting
  • user — user identification and preferences
  • tmax — maximum timeout for bid responses
  • at — auction type (1 = first price, 2 = second price)
  • bidfloor — minimum bid price per impression