n8n Lead Validation: Google Sheets Dedup + Slack Alerts

Instant lead validation with duplicate prevention + Slack notifications (n8n)

This n8n automation receives lead submissions via a webhook, checks them against your Google Sheets to prevent duplicates, validates email and Pakistani phone formats, saves the result to the right tab, and immediately alerts your team in Slack—valid leads to #valid-leads and invalid leads to #invalid-leads.

What this workflow does

• Receives a POST request on an n8n webhook endpoint containing lead details (name, email, phone number, and message).
• Loads existing leads from the Google Sheets tabs “Valid Leads” and “Invalid Leads” and aggregates rows for duplicate checking.
• Detects duplicates by comparing the incoming submission to stored rows; if a match is found, it stops processing.
• Validates inputs using JavaScript: verifies email format and a Pakistani phone number pattern of +92 followed by 10 digits.
• Routes and stores leads:
  • If valid: appends to “Valid Leads” and posts to Slack #valid-leads.
  • If invalid: appends to “Invalid Leads” and posts to Slack #invalid-leads.

Use cases

• Capture leads from a landing page form and instantly triage quality before sales follow-up.
• Prevent wasted outreach by stopping duplicate entries across both valid and invalid records.
• Enable real-time team awareness via Slack alerts whenever a submission fails validation.

Technical details

• n8n nodes / building blocks: webhook, aggregate, if, code (for JS email + Pakistani phone validation), no op, Google Sheets, and Slack.
• Google Sheets: Requires a spreadsheet with “Valid Leads” and “Invalid Leads” tabs.
• Slack: Uses Slack OAuth2 and posts to two configurable channels for valid vs. invalid leads.
• Setup: Update sheet references/tabs, add Google Sheets OAuth2, add Slack OAuth2, then configure your webhook URL.