Automate Interview Scheduling with n8n, Google Calendar & OpenAI

What This Workflow Does ⚙️

This workflow helps to schedule interviews automatically. It checks calendar busy times and finds free 30-minute slots during business hours in Eastern Time. Candidates chat with an AI assistant that offers available times and books interviews in Google Calendar. This saves lots of manual work and avoids double bookings.

The process starts when a candidate sends a message to the AI scheduler. It fetches calendar events for the next week, splits busy times into 30-minute blocks, and creates a list of all possible free slots on weekdays from 9 AM to 5 PM EST. The AI uses these slots to suggest times to candidates, collect their contact info, and confirm an interview.

Once confirmed, the workflow creates a Google Calendar event with candidate details. The candidate then gets a clear confirmation message. This removes back-and-forth emails, reduces errors, and saves about 5-6 hours every week for the HR team.

Who Should Use This Workflow

This is for people who schedule lots of interviews manually and want to save time. It works well for HR teams at busy companies with multiple interviewers and candidates.

Users should be comfortable with basic n8n workflow import and credential configuration. It is ideal if the scheduling happens in Eastern Time or time zones similar to New York City, but can be changed.

Tools and Services Used

• Google Calendar API: To read events and create new interview slots.


• OpenAI GPT-4o Mini: Powers the AI chat assistant for interactive scheduling talks.


• n8n Automation Platform: Runs the entire workflow, connecting triggers and actions.

Beginner Step-by-Step: How to Use This Workflow in n8n

Step 1: Download and Import Workflow

1. Click the Download button on this page to get the workflow file.


2. Open n8n editor and select Import from File.


3. Choose the downloaded workflow file to add it into n8n.

Step 2: Add Credentials and API Keys

1. In n8n, go to Credentials and create a new Google Calendar OAuth2 API credential with your Google account.


2. Create an OpenAI API credential using your OpenAI API key with GPT-4o Mini access.

Step 3: Update Workflow Settings

1. Find nodes referencing calendar emails (e.g., Check My Calendar) and replace the existing email with your calendar email.


2. If needed, adjust business hours or timezone settings in the Generate 30 Minute Timeslots node.


3. Customize AI system prompt in Interview Scheduler node if desired.

Step 4: Test the Workflow

1. Use the public webhook URL from When chat message received node to send a test chat as if you were the candidate.


2. Confirm the bot replies, suggests times, and books an event without error.

Step 5: Activate for Production

1. Turn on the workflow in n8n to start handling real scheduling requests.


2. Monitor executions via logs to catch any potential issues.

If self hosting n8n, consider using self-host n8n for better control.

Inputs, Processing, and Outputs Explained

Inputs

• Candidate sends chat message to public webhook URL.


• Google Calendar events for the next 7 days.

Processing Steps

• Fetch existing calendar events.


• Split busy times into 30-minute blocked slots.


• Generate all possible 30-minute weekday time slots during business hours (9-5 EST).


• Merge blocked and all slots to find free slots.


• The AI assistant uses availability info to propose free slots and collect candidate info.


• Parse AI output to JSON containing interview details.


• Create Google Calendar event with candidate data.

Outputs

• A calendar event booked without overlap.


• Clear confirmation message sent back to the candidate.

Customization Ideas

• Change business hours by editing businessStartHour and businessEndHour in the Generate 30 Minute Timeslots code node.


• Update timezone by replacing "America/New_York" with any preferred IANA string in date formatting nodes.


• Edit AI chatbot prompt in Interview Scheduler node to change behavior, questions, or tone.


• Use environment variables for calendar emails to handle multiple calendars across environments.


• Adjust interview length by changing 30-minute block logic in slot generation and event splitting nodes.

Common Issues and Fixes

Problem: "401 Unauthorized" or "Invalid Credentials" in Google Calendar nodes

Cause: OAuth2 credentials expired or misconfigured.

Fix: Re-create Google Calendar OAuth2 credentials and authorize the right Google account.

Problem: AI assistant gives no response or weird answers

Cause: OpenAI API key missing or system prompt errors.

Fix: Check OpenAI credential in n8n and improve AI node prompt format.

Problem: Candidate requested time conflicts with calendar busy slots

Cause: Calendar merging or filtering logic is wrong.

Fix: Verify Combine My Calendar with All Slots and Check if Calendar Blocked nodes have correct join and filters.

Pre-Production Checklist ✅

• Test Google Calendar OAuth2 credential with reading calendar events.


• Send a chat message to webhook and confirm AI replies as expected.


• Check that availability tool returns correct free slots in Eastern Time.


• Verify calendar events are created correctly without overlaps.


• Backup the workflow JSON before turning on production usage.

Deployment Guide

Enable your workflow inside n8n to start running live.

Share the public webhook URL with candidates so they can chat with the AI scheduler.

Watch execution logs in n8n dashboard for errors or slowdowns.

Change AI prompts or calendar logic as needed over time.

Summary

✓ Saves 5-6 hours per week by automating interview scheduling.

✓ Avoids double bookings and scheduling errors.

✓ Improves candidate experience with instant AI chat and confirmations.

✓ Uses Google Calendar API and OpenAI GPT-4o Mini for chat intelligence.

→ Simply import the workflow in n8n, add keys, and activate.

→ Easily customize business hours, timezone, or AI chat prompts.