Capture and deduplicate inbound leads with webhooks and Google Sheets

Quick overview

Capture inbound leads via webhook, validate and sanitize the data, deduplicate against Google Sheets, and store only clean leads ready to feed an AI-powered email/SMS nurture sequence.

How it works

1. Webhook receives the lead POST request from any form builder or landing page.
2. Validation Missing email or phone returns a 400 and stops execution.
3. Sanitize & normalize Trims whitespace, lowercases email, normalizes phone to international format, sets lead stage to 1, fills defaults for optional fields.
4. Dedupe check Looks up the email in Google Sheets; flags duplicates safely even when the sheet returns zero rows.
5. Duplicate → 200 "Already Registered", execution ends.
6. New lead → appended to Sheets, 200 "Lead Accepted" returned.

Setup

1. Import all 4 workflows they share one Google Sheet.
2. Create a sheet with these exact headers: Name, Email, Phone, Stage, Next Followup At, Has Replied, Lead Source, Service of Interest, SMS Consent
3. Connect Google Sheets OAuth2 in the Lookup and Append nodes; paste your Sheet ID/tab into the 🔧 CONFIG nodes.
4. Copy the webhook URL into your form builder. Map fields to: name, email, phone, lead_source, service_of_interest, sms_consent

Requirements

• Google Sheets (OAuth2)
• Gmail (OAuth2) used in Workflow 2
• A form/webhook source
• n8n instance with Workflows 2–4 also imported
• Part of a 4-workflow system: Lead Intake (this one) → Nurture Scheduler → Reply Listener → Daily Report.

Customization

• Add or remove fields Extend the Sanitize Data code node and the Sheets append mapping to capture any additional fields your form collects (e.g., company, budget, message).
• Change deduplication logic Currently deduplicates by email. Swap the lookup column to phone or add a second lookup node to deduplicate on both simultaneously.
• Swap the form source The webhook is source-agnostic. Replace a form builder with a CRM webhook, a Facebook Lead Ad integration, or a Zapier/Make relay as long as the payload keys match, nothing else changes.
• Adjust field defaults Modify the fallback values in the Sanitize Data node ('Friend' for name, 'Unknown' for lead source) to match your brand voice or CRM conventions.

Additional info

This is Workflow 1 of 4 in a complete AI lead nurturing system built for freelancers, agency owners, and solo founders:

Workflow 1 — Lead Intake (this template): Captures, validates, deduplicates, and stores leads
Workflow 2 — Nurture Scheduler: Sends AI-written email and SMS follow-ups across 3 stages
Workflow 3 — Reply Listener: Classifies lead replies with an LLM and escalates hot leads in real time
Workflow 4 — Daily Report: Emails you a morning summary of pipeline activity and follow-up counts