> ## Documentation Index
> Fetch the complete documentation index at: https://docs.versori.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Apps

> Within Switchboard, apps are the external-system nodes that you use to build out your integrations.

### What is an app?

An app is an external api or system that has been onboarded to Switchboard. Versori provides a number of public apps by
default, however the value of the platform is in the ability to onboard your own custom app connections to use within
Switchboard.

An App is currently one of the following types:

<CardGroup cols={1}>
  <Card title="REST API" href="/legacy/switchboard/how-to-guides/apps/onboarding-apps/rest-api">
    When onboarding a REST API, you upload an OpenAPI Specification (OAS) file. This file is used to generate the
    app's operations and available security schemes, as well as the available servers.
  </Card>

  <Card title="GraphQL API" href="/legacy/switchboard/how-to-guides/apps/onboarding-apps/graphql-api">
    When onboarding a GraphQL API, you provide an introspection url. This url is used to validate the queries and
    mutations that you create within Switchboard for the app.
  </Card>

  <Card title="SQL Database" href="/legacy/switchboard/how-to-guides/apps/onboarding-apps/sql-app">
    When onboarding a SQL Database, you create all of your SQL queries and also save those as operations.
  </Card>
</CardGroup>

When onboarding a REST API, you upload an OpenAPI Specification (OAS) file. This file is used to generate the app's
operations and available security schemes, as well as the available servers.

When onboarding a GraphQL API, you provide an introspection url. This url is used to validate the queries and mutations
that you create within Switchboard for the app.

When onboarding a SQL Database, you create all of your SQL queries and also save those as operations.

### What is an operation?

An operation is a single endpoint or action that is available on an app, as well as webhook subscriptions and callbacks.
Operations are created when you onboard an app, and can be created manually for SQL Databases and GraphQL APIs.