---
schema_version: "1"
id: f3706870f8b1a44232c6a0bc8e459f2e31aa2d9292bbd6a3b366530e49eb9b94
title: Authenticate with a Connected App
collection: developer
version: current
locale: en-us
portal_url: https://docs.salesforce.com/developer/current/en-us/service-cloud/salesforce-scheduler-dev-guide/guides/salesforce-scheduler/uc5-scheduler-api-auth.md
canonical_url: https://developer.salesforce.com/docs/service/salesforce-scheduler-dev-guide/guide/uc5-scheduler-api-auth.html
source_site: developer.salesforce.com
content_type: documentation
content_hash: 7e0681c45dfa676dddee2029af3bf9720f5661af3afe0b8b347709a33ea1c3ab
products:
  - Salesforce Scheduler Developer Guide
  - Service Cloud Developer Content
---

# Authenticate with a Connected App

The first step in an API-based integration is to connect to Salesforce and get an access token by using OAuth. OAuth access token authentication is the most secure way to authenticate SOAP and REST API calls.

**note:** It's not possible to modify an existing appointment via a guest user profile. You can use an integration user who has permissions to read and update only the required objects.

If you are working in a Salesforce organization that has a Developer Edition, an Enterprise Edition, or above, verify that you have the API Enabled permission. This permission is enabled by default. This permission allows you to access any Salesforce API.

When you have this permission, you can connect to Salesforce and authenticate. Then make a request to REST or Connect API and check the response. For more information, see [Connect REST API Quick Start](https://developer.salesforce.com/docs/atlas.en-us.chatterapi.meta/chatterapi/quickstart.htm).