PostMessage Inspector is a Chrome extension designed to simplify the debugging of postMessage communications between iframes and the main page. It adds a dedicated Post Messages tab to Chrome DevTools, enabling real-time visibility into every postMessage transaction across all frames and origins without requiring any configuration or coding. This tool is particularly useful for frontend developers, QA engineers, and security researchers who need to monitor iframe communications efficiently.

The extension offers features such as real-time message capture, powerful filtering options, and a full JSON payload viewer with syntax highlighting. Users can sort and resize columns, track message size and frame depth, and pause or resume the live feed without losing any data. It supports cross-origin communications seamlessly and allows for easy export of message sessions as JSON files, making it an invaluable asset for anyone working with iframe integrations.