REX: Research EXtensions
REX (Research EXtensions) is an open-source framework for building browser extensions for research on Chromium-based (Chrome/Edge) desktop platforms. REX is developed by BRIC (Behavioral Research Innovation Center), a 501(c)(3) nonprofit.
Is REX right for your study?
Section titled “Is REX right for your study?”REX has been used to support experimental studies where researchers change the behavior of certain websites for selected participants, observational studies of web behavior typically mixed with survey data, and in-depth interview-based studies. Some data from before extension installation can be included with participant consent if available.
Since REX has many highly customizable functionalities, we recommend exploring the documentation and trying the REX demo extension on the Chrome Web Store.
See the REX web page for more information.
Limitations
Section titled “Limitations”Extensions can only be installed in a desktop/laptop web browser, not on mobile devices (without a specialized mobile browser). Cross-device usage information is available from many platforms and may be accessible on desktop/laptop devices and thus to REX; that is, when a participant logs to an account they may have access to the history of the account across devices. BRIC has research app frameworks for Android and iOS for mobile device-specific observations.
Recommended path
Section titled “Recommended path”- Data Reference: browse data samples to see if they meet your needs. If not, please contact us. We are often able to add or modify a feature, or recommend another product.
- Getting Started: run the demo, download your own data to see if it matches your expectations (highly recommended)
- Local Backend: try the full server pipeline with Docker Desktop (optional)
- Decide how to distribute and collect data: see below
How do I collect data from participants?
Section titled “How do I collect data from participants?”There is no single answer: it depends on your study scale and participant relationship:
| Situation | Approach |
|---|---|
| Small study and/or known participants | Use rex-local-download to allow participants to download their data as a JSON file. Ask participants to upload their JSON to a secure file service (Box, Google Drive, etc.). See considerations. |
| Participants can load an unpacked extension | Skip the Chrome Web Store entirely. Share the dist/extension/ folder and walk them through loading it unpacked. |
| You want a polished install experience | Publish to the Chrome Web Store as Unlisted. Participants install via a direct link. See Publishing to the Chrome Web Store. |
| You want data flowing automatically to a server | Set up a PDK server (self-hosted or BRIC managed) and use rex-passive-data-kit. See Deploy. |
Already evaluated REX? Build your extension:
Extending REX (forking a module, contributing back, or both):
- Contributing to REX: covers the two paths: private fork for urgent work, or public contribution for shared/supported work
- Getting Placement Right: read before starting a contribution
- PR Checklist: run through before opening a PR
- Module Map
Documentation stages
Section titled “Documentation stages”| Stage | What you will do |
|---|---|
| Data Reference | Browse real data samples, no installation required |
| Explore | Run the demo, download your own data, decide if REX fits |
| Local Backend | Try the full server pipeline locally with Docker Desktop |
| Build Your Extension | Customize the starter template into your study extension |
| Deploy | If you need a server: self-host, use BRIC managed hosting, or hire BRIC to manage your server on your infrastructure. |
| Contribute | Contribute fixes or new features back to the public REX modules |
About BRIC
Section titled “About BRIC”REX is built and maintained by BRIC, a 501(c)(3) nonprofit focused on behavioral research infrastructure. The framework and this documentation are free to use. If REX is useful to your research, consider supporting BRIC’s mission. We will send you a donation acknowledgment for U.S. tax purposes.