Detect duplicate candidates from Gmail to Slack using Google Sheets

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

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

How to set up

1. Label candidate emails in Gmail with a label like applicant

2. Connect Gmail, Google Sheets, and Slack credentials in n8n

3. Create a Google Sheet with these columns:

   • candidate_name, candidate_email, candidate_phone, role_applied, years_of_experience, recruiter, resume_url, source_email

4. Import the workflow JSON

5. Update:

   • Gmail label ID
   • Google Sheet ID
   • Slack channel or user

6. 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

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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.