Blackbox API Visualizer

Visualize, diagnose, and trace API traffic directly inside Chrome DevTools.

Blackbox API Visualizer is a Chrome DevTools extension for understanding network and API traffic directly inside your browser. Instead of digging through hundreds of raw network requests, Blackbox organizes traffic into a developer-focused interface with request inspection, session analysis, and an interactive network graph. Features: • Capture network requests directly from Chrome DevTools • Inspect Fetch, XHR, documents, scripts, stylesheets, images, WebSockets, and other request types • View request URLs, headers, query parameters, bodies, response metadata, timing information, and initiator details • Explore an interactive graph of pages, domains, and API endpoints • Identify repeated requests, polling behavior, error clusters, slow requests, and large responses • Analyze top endpoints and domains across a DevTools session • Filter requests by type, errors, domain, and session insights • Inspect captured response bodies without replaying network requests Blackbox is designed for developers debugging unfamiliar applications, tracking API behavior, investigating performance issues, and understanding how a web application communicates with its backend services. Blackbox processes captured network information inside the DevTools extension and does not transmit captured traffic to a Blackbox server.