The Prebid team hosted a webinar to share updates on the state of Prebid Mobile, lessons learned since the release of SDK 3.0, and a preview of what’s to come with SDK 4.0. The session also featured case studies and best practices gathered from the growing publisher community adopting server-side and in-app header bidding.

The webinar was hosted by:

Christian Janelli – Director of Product Management at Prebid.

Mike Mullin – Vice Chair, Prebid Mobile at Prebid and Senior Product Manager at Index Exchange

Alex Fawcett – Prebid Mobile PMC Member and Head of Customer Success at Relevant Digital

José Brandenstein – Programmatic Ad Sales Manager at WetterOnline GmbH

Alexander Savelyev – Chair, Prebid Mobile at Prebid and VP Product at Verve

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Expanding Adoption of Prebid Mobile

Prebid Mobile continues to gain traction among publishers and app developers. The SDK is now integrated into over 2,000 apps worldwide, with daily downloads on the rise. The project’s open-source nature and collaborative development have driven broader participation from both independent publishers and ad tech partners.

One of the core advantages highlighted is that Prebid Mobile provides direct access to impression opportunities across apps, helping reduce duplicated supply and enabling cleaner, more transparent auctions.

Prebid SDK 3.0’s Achievements

Some main achievements of Prebid SDK 3.0:

• Plugin support now allows publishers to connect easily with bidders like Teads and InMobi, as well as identity or contextual data partners that need their own on-device code.
• Improved rendering performance, better support for rewarded video and multi-format ad units across iOS and Android.
• On iOS, continued investment in SKAdNetwork and AdAttributionKit aims to help capture more value from the growing gaming ad spend segment.
• A new API lets publishers modify bid requests and attach additional data without needing a full SDK update, which gives them more agility to experiment and optimise their setups.

Several bug fixes and enhancements introduced in 3.0 have helped make the SDK more reliable in production environments.

Looking ahead, SDK 4.0 is positioned as a major step forward. The roadmap focuses on:

• Streamlining the developer experience through easier setup and configuration
  
• Expanding format support beyond display to include richer and video inventory
  
• Enhancing performance monitoring and latency tracking
  
• Improving transparency and control for publishers over demand partner connections
  

Case Study: Lessons Learned from WetterOnline’s Prebid Mobile Integration

José Brandenstein from WetterOnline shared his team’s hands-on experience implementing the Prebid Mobile SDK. The main challenges revolved around SDK compatibility with other tools, such as Google’s SDK and ensuring seamless communication between app-side and server-side setups.

He emphasised the importance of keeping SDKs fully up to date and closely following Prebid’s release notes, since updates often include critical fixes for features like GPID and SKAdNetwork support. Missing a version can result in broken implementations or inaccurate reporting.

After upgrading to SDK 3.0, WetterOnline successfully activated GPID and SKAdNetwork integrations. Within two weeks, the team observed up to a 10% CPM uplift, confirming the value of consistent version maintenance and close coordination between ad ops, app developers, and SSP partners.

José also shared a simple tip: if reporting shows “unknown” GPID impressions, it usually means users haven’t updated to the latest app version yet, not a technical issue.

Best Practices for Prebid Mobile

Following the case study, Alex from Relevant Digital summarised four key best practices derived from WetterOnline’s experience and broader publisher feedback:

1. Use OpenRTB fields for flexibility: The newer SDK supports global and impression-level ORTB objects, making it easier to pass consistent data such as GPID and display manager info between web and app.
   
2. Ensure OMID compliance: Declare open measurement parameters (e.g., partner name, version, MRAID/OMID support) to signal transparency and enable accurate viewability tracking.
   
3. Check bidder vendor IDs: Before adding new bidders, confirm they’ve registered a Global Vendor ID to avoid compliance or performance issues in regions under GDPR or US privacy laws.
   
4. Implement ATT signals for iOS: Even if you choose not to track users, declaring App Tracking Transparency (ATT) status helps maintain compliance and future-proofs the app against Apple’s evolving privacy requirements.
   

Together, these practices make the Prebid Mobile SDK easier to maintain, more compliant, and better aligned with modern programmatic standards.

Prebid Mobile SDK 4.0 Roadmap

Alex from The Verve Group introduced the roadmap for Prebid Mobile SDK 4.0, outlining a clear mission: to give mobile publishers more control, transparency, and flexibility over their monetisation compared to closed mediation systems.

The roadmap is built around three main focus areas:

1. In-App Bidding Expansion: Broaden adoption by making integration easier across different app types and ad stacks (including gaming). This includes developing new mediation adapters, simplifying codebases for iOS and Android, and enabling partners like Teads and InMobi to build directly on the SDK via open APIs.
   
2. Creative Standardisation: Improve ad rendering consistency and measurement so that ads display and track correctly across formats, devices, and viewability vendors. The goal is to give buyers greater confidence and predictability in Prebid-powered inventory.
   
3. Prebid Mobile as a Platform: Modularise the SDK, improve documentation, and expand test coverage so developers can customise and extend it independently. The team aims to make Prebid SDK a developer-friendly, open platform that supports community-built extensions and automated testing.
   

Overall, SDK 4.0 will continue the shift from a basic in-app bidding tool to a flexible, open ecosystem that bridges publishers, developers, and demand partners under a standardised, transparent framework.

Q&A

1. How to better track impressions in in-app? BURL or ADM?
   Tracking in-app banner impressions typically follows the “one pixel in view” rule, with three main methods currently in use. Publishers can either include a BURL (bid URL) in their bid response and rely on the rendering SDK to fire it when the ad appears, use MRAID scripts within the creative to detect visibility (though results may vary across SDKs), or adopt OMID, the IAB Tech Lab’s open measurement standard that now has over 95% market adoption. The Prebid Mobile team is working to integrate OMID-based tracking directly into the SDK and Prebid Universal Creative, enabling automated impression firing once the visibility threshold is met, but for now, publishers can continue using BURL or MRAID tracking until OMID support is fully released.
   
2. How does the Prebid SDK perform compared to other mediation platforms, and are there plans to release more benchmarks or case studies to illustrate this?
   Prebid SDK isn’t meant to replace mediation platforms but to act as an additional demand source that can plug into existing mediation stacks. Its performance depends on the publishers’ connected bidders, SSPs, and DSPs, and while more benchmarks and case studies are needed, the first step was shown in the webinar’s earlier case study. Unlike traditional mediation, Prebid takes no revenue cut, meaning publishers get paid directly by advertisers or bidders. Prebid operates as an open-source, community-driven project, so data and feedback must come from publishers and partners using it.
   
3. With the GAM Prebid rendered integration method. Will we still use the PUC as with SDK 2.0?
   Prebid Universal Creative (PUC) and the Rendering API are two separate options. Publishers using PUC with an ad server such as GAM should continue using that setup, as it relies on Google’s WebView for rendering. However, those without an ad server, or looking to move away from one, can use the Prebid SDK’s native rendering to display banners, videos, and native ads directly. The SDK can also communicate with bidder plugins like Teads or InMobi, delegating rendering to them when needed. In short, publishers can either keep their current ad server workflow with PUC or adopt the SDK’s built-in or plugin-based rendering for more flexibility.
   
4. Any plans to support ad chain? Like Meta, they support showing multiple ads at once. It would increase the chance of winning against mediation or performance campaigns.
   Prebid is always open to the idea of bringing new ad formats, such as carousels, into the Prebid community discussions or GitHub issues, emphasising the goal of standardising innovative formats and moving them out of walled gardens into open programmatic environments.
5. Teads cannot work with GAM in the classic integration?
   Teads can already serve demand through the standard Prebid Server integration, but to access custom ad formats and advanced features offered by Teads, publishers need to use the Rendering API integration with the Teads plugin.