OpenWebUI MCP Server

OpenWebUI MCP – Subdomain Enumeration Tool

The OpenWebUI MCP server turns the popular OpenWebUI interface into a fully‑featured Model Context Protocol (MCP) provider. It solves the common pain point of bridging a conversational AI with external reconnaissance tools, enabling assistants to perform live subdomain enumeration without leaving the chat window. By exposing a dedicated “Subdfinder” tool through MCP, developers can add on‑demand network discovery capabilities to their AI workflows with minimal configuration.

At its core, the server runs a lightweight Flask application that serves an OpenAPI specification from the path. This spec defines a single MCP endpoint that accepts domain names and returns a structured list of discovered subdomains. The tool is implemented in Python using the popular library, which gathers data from a variety of passive sources such as certificate transparency logs and search engines. The MCP wrapper handles request validation, execution, and response formatting so that the AI assistant receives results in a consistent JSON schema.

Key capabilities include:

• Real‑time enumeration – The tool queries live sources, delivering up‑to‑date subdomain data during a conversation.
• Structured output – Results are returned as an array of domain strings, making them easy to parse and further process by downstream tools or scripts.
• Simple integration – Once the MCP server is running, any Claude‑style assistant that supports MCP can call the tool with a single instruction (e.g., “Use tool, generate subdomains for tesla.com”).
• Extensibility – The OpenAPI spec can be expanded to add filters, pagination, or additional reconnaissance methods without changing the core server code.

Typical use cases span security testing, threat intelligence gathering, and compliance audits. A penetration tester can ask the assistant to enumerate subdomains of a target domain, receive a list instantly, and then feed that list into automated scanning tools. Similarly, a DevOps engineer might use the tool to verify DNS records during infrastructure provisioning or to detect orphaned services exposed through subdomains.

By embedding subdomain discovery directly into the conversational layer, OpenWebUI MCP removes context switching between chat and command‑line utilities. Developers benefit from a unified interface, reduced friction in tool adoption, and the ability to orchestrate complex workflows—all while keeping the AI experience fluid and intuitive.