# Agent Guide {% hint style="warning" %} This page is not maintained anymore. The Agent guide is available in [Symphony Docs](https://docs.symphony.com/posts/5576418-agent-api-guide). {% endhint %} The **API Agent** is a component that is responsible for encrypting and decrypting the payloads of messages sent and received by an API caller, so that the caller does not need to implement encryption itself. The API Agent thus enables Symphony to provide a stable public API for application developers, even if the underlying Symphony private APIs undergo changes. This guide describes Symphony's public REST APIs and provides an overview of the technical infrastructure needed to support them. It is intended for infrastructure engineers who are planning to deploy the Agent or the Symphony REST API infrastructure in their organization. It provides an overview of network connectivity and infrastructure requirements for applications that call the REST APIs. Application developers and development managers who plan to develop REST API-based applications for Symphony may also find the contents of this guide useful background information. ### REST API Architecture Developers can use Symphony's REST APIs to create tools and applications for sending and receiving messages, user administration, and chat management. REST API endpoints are implemented on several physical interfaces: * The **Pod** is a cloud-based Symphony server infrastructure deployed in the cloud. * The **Key Manager** holds encryption key material for Symphony users. * The **Agent** provides encryption and decryption services for applications calling the Agent API. For security reasons, both the Key Manager and the Agent are typically deployed onsite at the customer's location; however, in some cases (for example, in testing environments) they may be deployed in the cloud. --- # Agent Instructions: 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: ``` GET https://docs.developers.symphony.com/admin-guide/agent-guide.md?ask= ``` The question should be specific, self-contained, and written in natural language. 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.