Webhook Queue & Retry in Google Sheets with Telegram Alerts

Queue, retry, and alert on webhook failures—using Google Sheets + Telegram

This n8n workflow securely receives authenticated POST webhooks, deduplicates and queues them in a Google Sheets “Webhook queue”, then retries delivery to your target HTTP endpoint on a schedule with exponential backoff. If delivery fails (or becomes permanently undeliverable), it sends Telegram alerts with the last status/error and re-queue instructions.

What this workflow does

• Receives incoming webhooks via an n8n webhook trigger secured with header authentication.
• Validates payloads to ensure the request body is a JSON object and small enough for Google Sheets; then creates a queue record using an Idempotency-Key / X-Event-Id header or body id (or a fingerprint) as the event key.
• Deduplicates in Google Sheets: checks for an existing row with the same key and responds immediately with 202 (queued) for new events or 200 (duplicate) for repeats.
• Processes retries every minute: reads the “Webhook queue” sheet and selects due items (pending/retry where next_attempt_at has passed) in small batches.
• Delivers with idempotency: POSTs each due payload to your configured target URL and passes the event key as the Idempotency-Key header.
• Updates status + backoff: records attempts, latest status/error, computes next_at using exponential backoff (optionally honoring Retry-After), and marks bad payload rows as failed without sending.
• Telegram notifications: sends alerts when items are failed or dead, including the last HTTP status/error and guidance for re-queuing.

Use cases

• Reliable webhook delivery for SaaS integrations when upstream systems occasionally send duplicates.
• Resilient retry handling for critical HTTP endpoints (payment events, status updates, event ingestion).
• Operational visibility with Telegram alerts for failed or permanently undeliverable webhook events.

Technical details

• Google Sheets tab: Webhook queue with columns key, received_at, source, status, attempts, next_at.
• Nodes used: if, set, code, webhook, telegram, and sticky note.
• Implements exponential backoff and retry scheduling based on next_attempt_at.