404NOT403

404NOT403 is an HTTP forensic tool designed for inspecting public URLs and analyzing detailed server responses. The platform allows users to perform forensic scans to see exactly what a server returns, including status codes, headers, TLS details, and indicators of CDN or web application firewall (WAF) presence. Its primary function is to reveal what the server actually says in response to requests, supporting users who require in-depth visibility into HTTP transactions.

Among its features, 404NOT403 offers a header inspector for examining any public URL and a system for conducting server-side forensic scans. Users can also monitor URLs over time through the Ghost Link Monitor, which tracks changes and detects when pages disappear or alter. Monitoring can be configured at intervals such as every hour, six hours, or twenty-four hours. The platform provides a status simulator, enabling users to trigger simulated HTTP responses like 404 Not Found or 403 Forbidden directly from the service. Additionally, there is a global activity feed that displays recent forensic events observed across the platform, including details such as URL, status, speed, server, and timestamp.

Access to 404NOT403 is managed through account creation and sign-in, with options to enable multi-factor authentication (MFA) for enhanced security. The tool is delivered as a web-based platform, as indicated by its online interface and account management features.

404NOT403 positions itself as a forensic HTTP instrument, serving users who need to inspect, monitor, and analyze server responses for public URLs. Its capabilities are suited to those seeking to understand server behavior, track changes over time, and simulate different HTTP status responses for testing or investigative purposes.