n8n Webhook Contact Deduplication & CSV Export Workflow

Clean, deduplicate, and audit your contact lists—then download a ready-to-review CSV

This n8n workflow accepts a contact list (via a manual demo or a POST webhook), normalizes and validates key fields, detects duplicates and same-email conflicts, and returns an UTF-8 CSV audit report with per-row status and a totals summary.

What this workflow does

• Triggers via Webhook or Manual Demo: Run a built-in sample dataset or send a webhook payload shaped like {"contacts": [...]}.
• Normalizes and validates contacts: Trims whitespace, standardizes casing, cleans phone formatting, and validates required fields such as name and email.
• Flags invalid records: Records missing required data are marked as needs_review; valid records move to the deduplication stage.
• Detects duplicates by email: Pending records are grouped by email to mark identical entries as ready/duplicate or flag same-email conflicts for review.
• Builds an audit-friendly CSV: Produces a spreadsheet-safe dataset for all rows, including reasons, duplicate references, and a totals summary. It also escapes spreadsheet-formula strings.
• Returns the file: Converts the audit dataset into a UTF-8 CSV and returns it as the workflow output (or directly as the webhook response).

Use cases

• Before importing contacts into a CRM, deduplicate by email and export only status = ready rows.
• Monitor data quality by routing malformed records to needs_review for correction.
• Detect conflicting records where the same email appears with different details, then review them safely via CSV.

Technical details

• Nodes used: Webhook, Code, Sticky Note, Convert to File, Manual Trigger
• Webhook input: application/json with a contacts array
• Batch guidance: Keep requests to 1,000 contacts or fewer per call