Online tracking remains problematic, with compliance and ethical issues persisting despite regulatory efforts. Consent interfaces, the visible manifestation of this industry, have seen significant attention over the years. We present robust automated methods to study the presence, design, and third-party suppliers of consent interfaces at scale and the web service consent-observatory.eu to do it with. We examine the top 10,000 websites across 31 countries under the ePrivacy Directive and GDPR (n=254.148). Our findings show that 67% of websites use consent interfaces, but only 15% are minimally compliant, mostly because they lack a reject option. Consent management platforms (CMPs) are powerful intermediaries in this space: 67% of interfaces are provided by CMPs, and three organisations hold 37% of the market. There is little evidence that regulators' guidance and fines have impacted compliance rates, but 18% of compliance variance is explained by CMPs. Researchers should take an infrastructural perspective on online tracking and study the factual control of intermediaries to identify effective leverage points.

Most modern applications are immutable and turn-key despite the acknowledged benefits of empowering users to modify their software. Writing extensible software remains challenging, even for expert programmers. Reprogramming or extending existing software is often laborious or wholly blocked, requiring sophisticated knowledge of application architecture or setting up a development environment. We present Varv, a programming model representing reprogrammable interactive software as a declarative data structure. Varv defines interactive applications as a set of concepts that consist of a schema and actions. Applications in Varv support incremental modification, allowing users to reprogram through addition and selectively suppress, modify, or add behavior. Users can define high-level concepts, creating an abstraction layer and effectively a domain-specific language for their application domain, emphasizing reuse and modification. We demonstrate the reprogramming and collaboration capabilities of Varv in two case studies and illustrate how the event engine allows for extensive tooling support.

We present Videostrates, a concept and a toolkit for creating real-time collaborative video editing tools. Videostrates supports both live and recorded video composition with a declarative HTML-based notation, combining both simple and sophisticated editing tools that can be used collaboratively. Videostrates is programmable and unleashes the power of the modern web platform for video manipulation. We demonstrate its potential through three use scenarios: collaborative video editing with multiple tools and devices; orchestration of multiple live streams that are recorded and broadcast to a popular streaming platform; and programmatic creation of video using WebGL and shaders for blue screen effects. These scenarios only scratch the surface of Videostrates' potential, which opens up a design space for novel collaborative video editors with fully programmable interfaces.