Create a Calendly Availability API Endpoint for Real-time Scheduling Data

Description

This n8n template implements a Calendly Availability Checker that provides real-time availability information for your Calendly event types via a simple API endpoint

Who's it for

This template is designed for developers, businesses, and service providers who need to programmatically check Calendly availability. It's perfect for:

Web developers** building custom booking interfaces that need real-time availability data
Chatbot developers** who want to suggest available times to users
Website builders** who want to display available slots on their site
Integration developers** who need to check availability before creating bookings
Businesses** that want to build custom scheduling experiences on top of Calendly
Service providers** who need availability data for their own applications or dashboards

How it works / What it does

This workflow creates a RESTful API endpoint that returns real-time availability information from your Calendly account. The system:

Accepts webhook requests via POST with optional parameters:
event_type_uri (optional) - Specific event type to check
days_ahead (optional, default: 7) - Number of days to check ahead

Authenticates with Calendly API using OAuth2 credentials to access your account

Retrieves user information to get your Calendly user URI and account details

Lists all active event types from your Calendly account

Selects the target event type:
Uses the event_type_uri from the request if provided
Otherwise defaults to the first active event type

Fetches available time slots from Calendly's availability API for the specified date range

Formats the availability data into a structured response including:
Total number of available slots
Next available slot (formatted and ISO timestamp)
Array of all available slots with formatted times and booking URLs
Slots grouped by day for easy consumption
Complete list of all event types

Returns a comprehensive JSON response with all availability information ready for integration

How to set up

1. Configure Calendly OAuth2 Credentials
Go to calendly.com/integrations
Click "API & Webhooks"
Create an OAuth2 application or use Personal Access Token
In n8n, create a new credential:
Type: "Calendly OAuth2 API"
Follow the OAuth flow to connect your Calendly account
The credential will be used by all HTTP Request nodes in the workflow

2. Activate the Workflow
Open the workflow in n8n
Ensure the Calendly OAuth2 credential is properly configured
Activate the workflow to make the webhook endpoint available

3. Test the Workflow
Use the "Test workflow" button in n8n to manually trigger it
Or send a POST request to the webhook URL:
{
"event_type_uri": "optional-event-uri",
"days_ahead": 7
}
Verify the response contains availability data
Check that the "Get Current User" node successfully retrieves your account info

4. Customize (Optional)
Adjust the default days_ahead value in the "Set Configuration" node (currently 7 days)
Modify the date range calculation in "Get Available Times" node
Customize the response format in "Respond with Availability" node
Add filtering logic to select specific event types
Add caching to reduce API calls

Requirements

Calendly account** with at least one active event type
n8n instance** (self-hosted or cloud)
Calendly OAuth2 API credentials** configured in n8n
Webhook access** (if using n8n cloud, webhooks are automatically available)

How to customize the workflow

Modify Date Range
Edit the "Set Configuration" node to change the default days_ahead value
Update the start_time and end_time calculations in "Get Available Times" node
Currently checks from tomorrow (1 day ahead) to 7 days ahead by default
Adjust the date calculation expressions as needed

Filter Specific Event Types
Modify the "Select Event Type" node to add filtering logic
Add an IF node to check event type names or slugs
Filter by duration, active status, or custom criteria
Return multiple event types if needed

Customize Response Format
Edit the "Respond with Availability" node to change the JSON structure
Add or remove fields from the response
Format dates/times differently
Include additional metadata from event types
Add pagination for large slot lists

Add Caching
Insert a Code node before "Get Available Times" to check cache
Store availability data temporarily to reduce API calls
Set appropriate cache expiration times
Consider using n8n's built-in cache or external storage

Add Error Handling
Enhance error handling in HTTP Request nodes
Add validation for request parameters
Return meaningful error messages in the response
Handle cases where no event types exist
Handle cases where no availability exists

Integrate with Other Services
Add nodes to log availability checks to a database
Send availability data to analytics platforms
Trigger notifications when availability changes
Sync availability with external calendars
Build availability dashboards

Key Features

RESTful API endpoint** - Simple POST endpoint for checking availability
Real-time availability** - Fetches current availability directly from Calendly API
Flexible event type selection** - Supports specific event type or auto-selects first available
Configurable date range** - Customizable number of days to check ahead
Comprehensive response format** - Returns formatted and raw availability data
Multiple data views** - Provides slots as array, grouped by day, and summary statistics
Event type information** - Includes details about all available event types
Human-readable formatting** - Formats dates and times for easy display
Booking URLs included** - Each slot includes direct booking URL
Error resilience** - Nodes configured with continueRegularOutput to handle API errors gracefully

Use Cases

Custom booking widgets** - Display available slots on your website without embedding Calendly
Chatbot integration** - Let AI assistants suggest available times to users
Mobile app integration** - Check availability before showing booking options in mobile apps
Multi-calendar systems** - Aggregate availability from multiple Calendly accounts
Availability dashboards** - Build internal dashboards showing team availability
Smart scheduling** - Check availability before sending meeting invitations
Booking confirmation flows** - Verify availability before processing bookings
Calendar sync verification** - Ensure Calendly availability matches other calendar systems
Analytics and reporting** - Track availability patterns and booking trends
Custom scheduling UIs** - Build completely custom scheduling interfaces using availability data

Data Fields Returned

User Information
User name, email, scheduling URL
User URI and organization URI

Event Type Information
Event type name, duration (minutes), URI
Complete list of all active event types with details

Availability Summary
has_slots - Boolean indicating if any slots are available
total_slots - Total number of available slots
next_available - Human-readable formatted string of next available slot
next_available_iso - ISO 8601 timestamp of next available slot

Available Slots Array
Each slot includes:
start_time - ISO 8601 timestamp
formatted - Human-readable date/time string
booking_url - Direct URL to book this specific slot

Slots by Day
Grouped object with days as keys
Each day contains array of time slots with formatted times and booking URLs
Format: { "Monday, Dec 2": [{ time: "10:00 AM", url: "..." }] }

Metadata
checked_at - ISO timestamp of when availability was checked
success - Boolean indicating successful execution

Workflow Architecture

The workflow uses a linear processing pattern with data transformation at each step:

Webhook Trigger → Receives POST requests with optional parameters
Set Configuration → Extracts and sets default values for event_type_uri and days_ahead
Get Current User → Authenticates and retrieves Calendly user information
Extract User Info → Parses user data to extract URIs and account details
Get Event Types → Fetches all active event types for the user
Select Event Type → Chooses target event type (from request or first available)
Get Available Times → Queries Calendly API for available time slots
Format Availability → Transforms raw API data into structured, formatted response
Respond with Availability → Returns comprehensive JSON response to caller

Example Scenarios

Scenario 1: Check Default Availability
Developer sends POST request to webhook endpoint with empty body
Workflow uses default 7-day lookahead period
Workflow selects first active event type automatically
Returns availability for next 7 days with all slots formatted
Developer displays slots in custom booking interface

Scenario 2: Check Specific Event Type
Developer sends POST request with specific event_type_uri
Workflow uses provided event type instead of default
Checks availability for that specific event type only
Returns slots grouped by day for easy calendar display
Developer shows availability in day-by-day calendar view

Scenario 3: Extended Date Range
Developer sends POST request with days_ahead: 30
Workflow checks availability for next 30 days
Returns comprehensive list of all available slots
Developer uses data to show monthly availability view
User can see all available times for the next month

Scenario 4: Chatbot Integration
User asks chatbot "When are you available?"
Chatbot calls webhook endpoint to get availability
Workflow returns next available slot and total count
Chatbot responds: "I have 15 slots available. Next available: Monday, Dec 2 at 10:00 AM"
Chatbot offers to book the next available slot

This template provides a powerful API endpoint for checking Calendly availability, enabling developers to build custom scheduling experiences while leveraging Calendly's robust scheduling infrastructure.