What is Prebid?

Prebid is a free, open-source header bidding solution made up of a product suite (including Prebid.js, Prebid Server and Prebid Mobile), a developer community and an independent organisation, Prebid.org, that maintains it.

Also known as: Prebid.js, Prebid.org

How it works

Prebid is one way to do header bidding, and the distinction matters. Header bidding is the technique of asking several demand partners for bids before the ad server decides. Prebid is the open-source code, and the organisation behind it, that many publishers use to put that technique into practice.

The suite has three main parts, as described in Prebid's documentation (Prebid):

  • Prebid.js is a JavaScript library that runs in the browser. It supports display, video and native formats and is the core product most web publishers start with.
  • Prebid Server runs the auction server-to-server. Its documentation lists use cases including mobile apps, AMP pages, server-side web setups and server-side ad insertion for CTV, digital out-of-home and audio (Prebid Server overview).
  • Prebid Mobile provides SDKs (software development kits) for iOS and Android so apps can run header bidding.

Prebid talks to demand through bid adapters, small modules that handle the conversation with each SSP, DSP or exchange. It sends requests to the chosen bidders at the same time, and any bidder that has not answered within the timeout is left out of that auction (Prebid). The winning bids are then passed to the ad server as key-values so they can compete with the publisher's other demand.

Who runs Prebid?

Prebid.org describes itself as an independent membership organisation of ad tech companies. It is funded by membership dues rather than by taking fees on revenue, and the code, demos and documentation are released under the Apache License, so anyone can read, use or contribute to them on GitHub (Prebid). Prebid Server can be self-hosted, although the documentation is frank that this is much harder than setting up Prebid.js, and several Prebid.org members offer hosted versions (Prebid Server overview).

Why it matters

Because Prebid is open and free, publishers are not locked into one vendor's wrapper and can see exactly how their auction works. The flip side is responsibility. Someone still has to choose bidders, set timeouts and floors, keep adapters up to date and make sure the ad server is configured to receive the bids correctly.

Example

Example (illustrative)

A gaming news site runs Prebid.js on its web pages with a handful of bid adapters. When it launches a mobile app, it uses Prebid Mobile in the app and points it at a hosted Prebid Server, so the app's inventory can join the same kind of competitive auction without running bidding code on the phone itself.

IncrementX perspective

Prebid gives publishers the machinery; getting value from it depends on the partners connected, the configuration and ongoing tuning. IncrementX offers header bidding support that includes wrapper setup support, demand partner integration and performance optimization, alongside its representation work. For a longer read, see What Is Pre-Bid Technology and Why Do Most Publishers Use It?.