WhatWeb is a web scanner that identifies technologies powering websites through automated plugin-based detection.
WhatWeb solves the problem of quickly determining what technologies, frameworks, content management systems, and web servers are running on a target website. It works by maintaining a library of over 1800 plugins, each designed to recognize specific technologies through various detection methods. Rather than relying on a single identifying marker, most plugins employ multiple detection techniques—for example, the WordPress plugin checks for generator meta tags, favicons, default installation files, login pages, and characteristic URL patterns. This multi-faceted approach allows the tool to identify technologies even when obvious indicators have been removed or obscured. The tool supports configurable aggression levels, ranging from a stealthy single-request scan suitable for public websites to more thorough modes that interrogate targets more extensively for penetration testing scenarios.
WhatWeb suits security professionals and penetration testers who need to quickly enumerate web technologies during reconnaissance. The stealthy default mode makes it appropriate for scanning public websites with minimal footprint, while higher aggression levels serve penetration testing engagements where more thorough identification is required. The tool's extensive plugin library and support for version detection, email address extraction, and error message identification make it valuable for detailed asset discovery. It offers multiple output formats including JSON, XML, and database-compatible formats, enabling integration into security workflows and reporting pipelines. Performance tuning options allow concurrent scanning with automatic output optimization, making it practical for large-scale assessments.
The project maintains active development with regular updates and bug fixes. The codebase shows ongoing refinement of detection capabilities and performance optimization. Documentation is comprehensive, with a dedicated wiki and inline help, suggesting attention to usability for both new and experienced users. The tool continues to expand its plugin ecosystem to recognize emerging web technologies and frameworks.
