Introduction

All is not well in our digital ecosystem. The social media platforms through which we as citizens engage with what is going on in the world are designed to optimise for engagement. This business model underpinning how news and public debate gets prioritised and framed risks fragmenting users into separate information bubbles. Engagement based ranking tends to surface inflammatory and divisive content. The voices and perspectives that are recommended online are not representative of the spectrum of public opinion but skewed towards polarized, extreme or contrarian positions.2 Our cognitive bias toward sensationalist content interacts with recommender algorithms to create feedback loops where we as voters see more and more extreme content.

Online polarization has real world offline consequences. It affects which topics are discussed and how we discuss them in our families, workplaces and communities. This shaping of civic discourse frames political debate with consequent impact on electoral outcomes.3 Social cohesion and public security is jeopardised by divisive narratives, including on violence or terrorism, that get amplified triggering spirals of public disorder, threats and violence against ‘out groups’ within our society or channelled toward foreign adversaries.

Public debate in Europe shows a growing awareness of this systemic risk of how Very Large Online Platforms (VLOPs) operate. But can we actually measure where, when and how online polarization is happening, and on which specific platforms? And then what can be done about it?

This report aims to provide some answers to these questions in the EU context. It starts out by explaining the conceptual framework behind the polarization footprint. It then sets out the methodology that has been used to calculate the polarization footprint across social media platforms. The report then connects the polarization footprint concept to the systemic risk framework of the Digital Services Act (DSA) with a focus on civic discourse and public safety before going on to explore the wider relevance of the polarization footprint to the EU’s internal and external policies.

Many jurisdictions are exploring public policy responses to online harms. For the EU this has meant forging political consensus around a set of values and principles which are expected to be upheld by actors in the digital space. The DSA translates this policy ambition into an EU wide legal framework for platform governance which seeks to uphold the rights of 450m Europeans with enhanced transparency, identification of systemic risks and, through a co-regulation model, ultimately drive technological design changes towards more prosocial outcomes.

Authors & Acknowledgments:

This paper was authored by Guy Banim at Build Up. It was edited and developed with guidance from Helena Puig Larrauri, Luke Thornton and Rita Costa Cots at Build Up and Daniel Burkhardt Cerigo at datavaluepeople. With many thanks to Laura Batalla Adam at Ashoka for the support and opportunity to test ideas during the September 2025 launch of the Ashoka Participation Hub1 and to Claudia Meier for the trail that was blazed, in particular with the opportunity for brainstorming at the European Forum Alpbach 2025. Thanks also to Ravi Iyer and Lena Slachmuijlder for always inspiring discussion in Brussels and beyond. The report also benefitted from discussions during a dedicated session at the EU Community of Practice on Peace Mediation in October 2025. Thanks above all to the dedicated team and all those who engaged in the polarization footprint pilot study in Kenya: this gives the report the crucial evidence base needed to drive the change we wish to see.

To cite: Banim, G. (2025). “Very Large Online Platforms—How big is your Polarization Footprint?” Towards a metric to give EU citizens transparency around an online systemic risk driving conflict in our societies. Build Up ˆ.