postMessage-tracker-f

postMessage-tracker-f is a Firefox extension designed to monitor postMessage listeners effectively. It provides a visual icon indicator displaying the number of active listeners in the current window, including all subframes, and highlights potentially vulnerable functions. This powerful tool logs detailed listener information—such as URL, domain, and call stack—via CORS to a configurable endpoint, enabling in-depth analysis of message event listeners, including short-lived and interaction-enabled ones.

Built as a super simple port of the original extension by Frans Rosén, postMessage-tracker-f supports unwrapping listeners wrapped by popular frameworks like Raven, New Relic, Rollbar, Bugsnag, and jQuery to reveal the actual listener functions. It also reroutes wrappers for clear DevTools console visibility. The extension aids developers and security professionals in auditing cross-window communication, detecting hidden or suspicious listeners, and enhancing web application security. Fully open-source, it encourages community contributions and bug reports through its GitHub repository.