> For the complete documentation index, see [llms.txt](https://docs.serverlessapigateway.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.serverlessapigateway.com/glossary/p/plugin.md). # Plugin A plugin (also called an extension or add-on) is a software component that adds specific functionality to an existing application without modifying its core code. Plugins conform to the host application's defined extension points and APIs, allowing third-party developers to extend capabilities in a modular way. Plugins are central to the extensibility model of many software tools, including IDEs (VS Code extensions), content management systems (WordPress plugins), and browsers (Chrome extensions). The plugin architecture allows the core application to remain lightweight while users add only the functionality they need. In API gateway contexts, plugins extend gateway behavior with additional processing logic. Many API gateways support plugin systems for adding custom authentication methods, logging integrations, response transformations, and protocol translations. For example, an API gateway might offer plugins for JWT validation, OAuth token introspection, IP whitelisting, or request/response body modification. This plugin model allows teams to customize their gateway without forking or modifying the core gateway code. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.serverlessapigateway.com/glossary/p/plugin.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.