n8n Webhook Deduplication Workflow with Data Table & Telegram

Deduplicate incoming webhook enquiries in n8n—and notify your team on Telegram only once

This n8n Webhook Deduplication Workflow receives enquiry POSTs, prevents duplicate submissions using an idempotency key stored in an n8n Data Table, classifies accepted enquiries by configured keywords, and sends formatted Telegram notifications. Failed processing is automatically retried on a schedule until it succeeds or becomes a dead letter.

What this workflow does

• Receives webhook enquiries via a POST endpoint and loads configurable settings (required fields, deduplication window, retry limits).
• Validates inputs and immediately returns HTTP 422 if required fields are missing.
• Builds an idempotency key from Idempotency-Key / X-Request-Id headers, or falls back to a SHA-256 hash of a normalized request body.
• Checks the n8n Data Table for a recent matching record: duplicates return HTTP 200, while new requests are logged and returned as HTTP 202 accepted (with a race-condition guard that keeps the earliest copy).
• Processes saved payloads: classifies into priority and category using configured keywords, then sends a formatted message to Telegram.
• Tracks outcomes in the Data Table: marks rows as done on success, or records errors, increments attempts, and sets failed/dead when max retries is reached (including a Telegram alert for dead letters).
• Retries automatically every 15 minutes by finding stored “received/failed” rows that have waited long enough.

Use cases

• Prevent repeated form submissions or webhook retries from spamming your sales/support channels.
• Route and prioritize inbound enquiries (e.g., “urgent” vs “general”) using keyword-based classification.
• Ensure reliable Telegram notifications with scheduled retry handling for transient failures.

Technical details

• Nodes / components: webhook, if, set, code, telegram, data table.
• Deduplication storage: n8n Data Table with an idempotency key and deduplication window.
• Scheduling: runs every 15 minutes to retry processing.

Category: n8n automation workflow