--- title: "Components of Catalyst Serverless" url: https://docs.catalyst.zoho.com/en/serverless/getting-started/components-of-serverless/ description: "Learn about getting started with Catalyst Serverless that provides powerful FaaS and PaaS solutions for multiple environments." last_updated: 2026-08-17T12:16:04Z service: Serverless type: general --- # Components of Catalyst Serverless **FAAS** - [Functions](https://docs.catalyst.zoho.com/en/serverless/help/functions/introduction/)Custom-built coding structures which contain the intense business logic of your application. - [Security Rules](https://docs.catalyst.zoho.com/en/serverless/help/security-rules/introduction/)Define the invocation and access rules of your Serverless Basic I/O and Advanced I/O functions **COMPUTE** - [AppSail](https://docs.catalyst.zoho.com/en/serverless/help/appsail/introduction/) Build and host solutions of any scale in any framework of Java, Node.js, or Python, with this powerful PaaS. **ORCHESTRATION** - [Circuits](https://docs.catalyst.zoho.com/en/serverless/help/circuits/introduction/)Orchestrate tasks and automate workflows in Catalyst. As represented above, Catalyst Serverless includes the following components: * Functions * AppSail * Circuits * Security Rules ### Functions [Serverless Functions](https://docs.catalyst.zoho.com/en/serverless/help/functions/introduction/) are custom-built coding structures that contain the core backend logic of your application or service. Using Serverless Functions reduces your code setup, building, and maintenance efforts and the time you would typically spend before starting to code your logic. - Serverless offers the following functions types and templates for various purposes: - [**Basic I/O Function**](https://docs.catalyst.zoho.com/en/serverless/help/functions/basic-io/): Code basic input/output operations and simple HTTP operations between the various components of Catalyst services. - [**Advanced I/O Function**](https://docs.catalyst.zoho.com/en/serverless/help/functions/advanced-io/): Access the ideal code structure to use multiple APIs and handle native HTTP responses between the components of various Catalyst services. You can also code complex server-client operations, and parse and channel large volumes of data. - [**Integration Function**](https://docs.catalyst.zoho.com/en/serverless/help/functions/integration-functions/): These functions offers you the advantage of using a Serverless function on the backend to perform operations in other Zoho services by establishing an integration with them. - [**Event Function**](https://docs.catalyst.zoho.com/en/serverless/help/functions/event-functions/): This type of function can be used to handle event-based logic triggered by [Catalyst Signals](https://docs.catalyst.zoho.com/en/signals/). You can use this function to execute an operation, or a set of operations, after the occurrence of a configured event. - [**Cron Function**](https://docs.catalyst.zoho.com/en/serverless/help/functions/cron-functions/): [Cron](https://docs.catalyst.zoho.com/en/cloud-scale/help/cron/introduction/), a component of [Catalyst Cloud Scale](https://docs.catalyst.zoho.com/en/cloud-scale/getting-started/introduction/), is an automatable job scheduler. This type of function can be coded as a periodic function associated with a configured Cron. - [**Browser Logic**](https://docs.catalyst.zoho.com/en/smartbrowz/help/browser-logic/introduction/): You can code [browser logic](https://docs.catalyst.zoho.com/en/smartbrowz/help/browser-logic/implementation/) functions that can be used to perform any task you would manually do in a browser. The [SmartBrowz](https://docs.catalyst.zoho.com/en/smartbrowz/getting-started/introduction/) Catalyst service lets you control and manage a browser through code and the Browser functions lets you code in the business logic to ensure the same. Each of these function types can be initialized in [**Java**](https://docs.catalyst.zoho.com/en/sdk/java/v1/overview/), [**Node.js**](https://docs.catalyst.zoho.com/en/sdk/nodejs/v2/overview/), or [**Python**](https://docs.catalyst.zoho.com/en/sdk/python/v1/overview/), and when you initialize these functions you will be provided with a customizable boilerplate for coding your logic faster. ### AppSail The [AppSail](https://docs.catalyst.zoho.com/en/serverless/help/appsail/introduction/) component is a powerful platform-as-a-service (**PaaS**) offering, with which you can build and host any scale of applications from simple microservice to large enterprise solutions, even independently of Catalyst, in the supported development environments. You have the flexibility to code using any framework without any restrictions, incorporate and manage any dependencies, and efficiently manage the platform of your service after you deploy it. AppSail will ensure the required server instances are generated and are scaled based on the needs. The platform management feature enables you to view the generated instances, set thresholds, view statistics and reports of the instances, and terminate them manually, when needed. These reports offer crucial aid during the debugging stages. ### Circuits With [Circuits](https://docs.catalyst.zoho.com/en/serverless/help/circuits/introduction/), you can orchestrate and automate workflows in your Catalyst application directly from the console. Use circuits to implement concurrent or sequential executions of [Serverless' Basic I/O Functions](https://docs.catalyst.zoho.com/en/serverless/help/functions/basic-io/). You can manage and execute multiple parallel processing tasks, configure conditions, incorporate data, and design workflows that repeatedly execute tasks for any desired outcome. There are several [Circuit states](https://docs.catalyst.zoho.com/en/serverless/help/circuits/key-concepts/#circuit-states-1), flow control options, and input and output paths you can utilize to design a comprehensive workflow. Catalyst enables you to use the drag-and drop builder to construct complex workflows in a few simple steps from the console. You can design a workflow with any scale of functionality, and as elaborate or as simple as you require based on your requirements. ### Security Rules The [Security Rules](https://docs.catalyst.zoho.com/en/serverless/help/security-rules/introduction/) component fulfills fundamental requirements for securing [Basic I/O](https://docs.catalyst.zoho.com/en/serverless/help/functions/basic-io/) and [Advanced I/O](https://docs.catalyst.zoho.com/en/serverless/help/functions/advanced-io/) endpoints. Security Rules is a `JSON` file which contains the security definitions of the function, including the HTTP methods that can be accessed by a function, and whether authentication is necessary to access the function's endpoint. You can configure these based on your requirements. Security Rules is automatically enabled by Serverless when a Basic I/O or an Advanced I/O function is created in the console, or initialized locally using the [Catalyst CLI](https://docs.catalyst.zoho.com/en/getting-started/installing-catalyst-cli/) and deployed to the console.