REX: Research EXtensions

The REX framework helps researchers collect data and/or perform experimental interventions using a web browser extension on the participant's desktop or laptop computer. While the extension runs only on the desktop, some modules can collect data at the account-level (e.g. ChatGPT). Thus any conversation on that account (mobile, desktop, web) would be included.

While web browser extensions may not be a common technology for social and behavioral research data collection, extensions are used widely to modify real web pages to block advertisements.

At BRIC our co-founders have been using browser extensions in research projects since 2016. For example, our Technology Director, Chris Karr, built the browser extension for a field experiment by economists at Stanford, the University of Pennsylvania, and MIT studying why Google dominates web search (Allcott et al., 2025). Google users in the study were paid to use Bing for two weeks, and the extension recorded their searches. For some participants, it also invisibly degraded Bing's results by reversing their order on the page, so the last result appeared first and the top result appeared last. Those participants rated Bing's results as less relevant than participants who saw the normal order, and they clicked the top link far less often. Yet their continued use of Bing barely changed, and the drop was not statistically significant. The authors conclude that users may place limited weight on result relevance when choosing a search engine. This finding, made possible by the extension, was cited throughout the September 2025 remedies decision in United States v. Google (Memorandum Opinion).

Try the researcher demo extension that collects data locally (json file) to help you determine if it can work for your study. Here is a notebook that can help you see what you have in your download from the REX demo.

See the REX Documentation for more details about how to implement the framework for your project.