Detect duplicate candidates from Gmail to Slack using Google Sheets

Description

Detect duplicate candidates by email/phone from Gmail to Slack using Google Sheets

This workflow automatically detects duplicate job applicants by checking incoming emails from Gmail against existing records in Google Sheets.
If a candidate's email is already found in the sheet, it sends an alert to Slack; otherwise, it adds the candidate to the sheet.

Who’s it for

HR and recruitment teams processing candidate emails manually
Startups or SMEs handling job applications via Gmail
Anyone who wants to automate resume collection and deduplication
Teams using Slack and Google Workspace

How it works

Triggers every few minutes via the Schedule Trigger node
Fetches recent emails labeled "applicant" from Gmail
Extracts candidate details from the email body using regex
Reads all existing rows from the Google Sheet
Compares the candidate’s email with existing entries
If duplicate → Sends a Slack alert
If new → Appends to the Google Sheet

How to set up

Label candidate emails in Gmail with a label like applicant
Connect Gmail, Google Sheets, and Slack credentials in n8n
Create a Google Sheet with these columns:

candidate_name, candidate_email, candidate_phone, role_applied, years_of_experience, recruiter, resume_url, source_email
Import the workflow JSON
Update:
Gmail label ID
Google Sheet ID
Slack channel or user
Activate the workflow

Requirements

n8n (self-hosted or cloud)
Gmail account with access to labeled application emails
Google Sheet to store candidates
Slack account with chat:write scope
Basic regex familiarity (optional)

How to customize

Change comparison logic to include phone numbers.
Add fallback logic to check for similar names.
Add filters for roles, experience levels.
Forward resumes to Drive or Notion.
Trigger an approval flow for screened candidates.

Add‑ons

Google Drive: Upload parsed resumes.
Notion / Airtable: Store structured candidate records.
Webhooks: Forward to ATS or CRM.
PDF parsers: Extract data from attachments.

Use Case Examples

| Use Case | Description |
| ------------------- | ----------------------------------------------------- |
| Resume deduplication | Avoid processing the same applicant twice |
| Auto Slack alert | Instantly notify recruiter of repeat candidates |
| Centralized tracking | Keep candidate records in Sheets for filtering/export |
| Passive sourcing | Run hourly checks on labeled Gmail inboxes |

Common troubleshooting

| Issue | Possible Cause | Solution |
| ------------------------ | ------------------------------------------ | -------------------------------------------------------------- |
| Slack message not sent | Invalid Slack token / channel not selected | Reauthorize Slack connection and select correct user/channel |
| Google Sheet not updated | Sheet ID or tab name is incorrect | Double-check the Sheet URL and worksheet tab |
| Email data not extracted | Email body format doesn’t match regex | Adjust regex in the "Code" node |
| Nothing happens | Gmail label or date filter is too strict | Ensure emails exist with the right label in the last X minutes |

Need Help?

Need help setting it up or tweaking regex for your custom email format? We’re happy to help — just ask!

Want to add phone number duplication checks or auto-resume upload to Google Drive? Our Automation team at WeblineIndia can guide you step-by-step.