INTERCEPT is a self-hosted, open-source web application for signal intelligence (SIGINT) and spectrum monitoring. It provides a unified dashboard to control Software Defined Radios (SDRs) and decode over 20 wireless protocols, including ADS-B (aircraft), AIS (ships), ACARS/VDL2 (airline data), POCSAG/FLEX (pagers), APRS, Bluetooth, WiFi, satellite imagery (SSTV/weather satellites), and drone remote ID. It also features a dedicated Technical Surveillance Counter-Measures (TSCM) suite for detecting hidden devices and Bluetooth trackers. Built as a Flask monolithic application, it orchestrates external SDR tools as subprocesses, parsing their output and streaming decoded data to a real-time web UI via Server-Sent Events (SSE) and WebSockets. The architecture features a clean SDR hardware abstraction layer (Strategy pattern), a centralized event pipeline for alerts and data persistence, and a modular JavaScript frontend with reusable components. It supports distributed operation via remote agents. While primarily an application, it contains significant data engineering components for processing RF data, including signal databases, heuristic engines for Bluetooth tracker detection and WiFi channel analysis, and RSSI-based trilateration algorithms. It is designed for security researchers, radio enthusiasts, and TSCM professionals. The codebase demonstrates high craftsmanship with extensive test coverage (including a novel FakeProcess test utility), clean abstractions, and active maintenance. It is a strong example of a complex, hardware-integrated web application, though its monolithic nature and heavy reliance on specific external tool versions introduce some technical drift risk.