Shannon is an open-source autonomous AI penetration tester developed by KeygraphHQ that combines agentic source-code analysis with live exploitation against running web applications and APIs. The tool performs multi-stage security testing: it maps application architecture, trust boundaries, data flows, and critical assets through code analysis while simultaneously conducting runtime reconnaissance across injection, XSS, SSRF, authentication, and authorization categories. Findings from both streams are reconciled and deduplicated into an exploitation queue where agents execute real proof-of-concept attacks using browser automation (Playwright) and command-line tools inside an ephemeral Docker worker container. Only vulnerabilities with demonstrated exploits are reported, eliminating speculative scanner noise. Shannon supports Anthropic, OpenAI, xAI, AWS Bedrock, and any Pi-compatible provider or local model via Ollama, vLLM, or LM Studio with custom base URLs and model configurations, operating on a bring-your-own-key basis without proxying traffic. It integrates natively with GitHub Actions and GitLab CI/CD, preserving PDF, Markdown, JSON, and SARIF 2.1.0 artifacts, and can gate pipelines on exploited findings at configurable severity thresholds. Requirements include Docker, Node.js 18+, and provider cyber safeguards clearance. A full scan takes roughly 1-1.5 hours and incurs LLM API costs. Licensed under AGPL-3.0, Shannon targets the "long tail" of under-tested internal apps and fast-moving services, shifting pentesting left into the SDLC while complementing—not replacing—expert human pentesters.