Ticketing Backend automates registration, QR-ticket generation, email delivery, and check-in validation using Google Sheets, Gmail, and a webhook scanner — reducing manual ticket prep from ~3 hours to under 5 minutes for 200 attendees. Why Use This Workflow? Time Savings: Automates ticket generation & delivery. reduces manual processing for 200 attendees from ~3 hours to 90%. Scalability: Runs on a schedule and webhooks; scales from dozens to thousands of tickets (watch API/email quotas). Ideal For Event Organizers / Community Managers: Sell & distribute tickets for meetups, runs, and local events with immediate QR delivery. Operations / Venue Staff: Fast, reliable check-in via mobile scanner POSTing to webhook for instant validation. Small Agencies & SaaS Teams: Lightweight, low-cost ticketing backend that integrates with existing Google accounts. How It Works Trigger (Registration): POST /v1/register receives registration payload (nama, email, no_hp, jumlah_tiket, total_price, payment_method). Data Collection (Registration): Validate input → check existing participant in Register sheet → append registration. Processing (Ticket Generation): Scheduled job (START runs every minute) finds rows with Payment Status = PAID and Email Sent = NO. Intelligence Layer: For each ticket: generate unique Ticket ID (TL-YYYYMMDD-XXXX-N-HASH), build QR payload JSON, create QR image via qrserver API, and build HTML email with embedded base64 QR. Output & Delivery: Send ticket email(s) via Gmail; write one Tickets row per generated ticket and mark Email Sent = YES in Register. Storage & Logging: All participant & ticket records persisted to Google Sheets; check-in events update row (Checked In = YES and Checkin TIme). Core Endpoints Registration webhook: POST /v1/register Scanner webhook (check-in): POST /v1/scanner Event Metadata Event: TABRAK_LARI Event date: 15 November 2025 Event location: GOR Pontianak Setup Guide Prerequisites Requirement Type Purpose n8n instance Essential Host the workflow and webhooks Google account (Sheets + Gmail) Essential Store tickets & send emails Google Sheet Essential Register & Tickets data store Public webhook URL / reverse proxy Essential Expose /v1/register & /v1/scanner to scanners/clients qrserver.com (public API) Optional Generate QR images (no credentials) Important: Make sure your n8n instance URL is publicly accessible or use a tunneling/reverse proxy so webhooks can receive POSTs. Installation Steps Import the JSON into your [n8n instance( https://n8n.partnerlinks.io/khmuhtadin ). Configure credentials: Google Sheets OAuth2: Grant access to Google Drive & Sheets API (spreadsheets.readonly & spreadsheets). Gmail OAuth2: Grant send email scope (Gmail send). Update environment-specific values: Verify Google Sheet ID. Set the public base URL for ticket scanner clients to POST /v1/scanner. Customize settings: Event name/date/location (variables in Generate Ticket Data / Build HTML Email). Email sender address and subject line in Gmail node. Test execution: Use a sample POST to /v1/register with valid fields to create a registration. Mark a row as PAID and Email Sent = NO to trigger scheduled ticket generation. Simulate a scanner POST to /v1/scanner with the barcode JSON payload to test check-in. Technical Details Core Nodes Node Purpose Key Configuration REGISTER (Webhook) Accepts registration POSTs Path: /v1/register Validate Input (Code) Server-side validation Validates nama, email, no_hp, jumlah_tiket, payment_method Get Participant (Google Sheets) Check duplicate email Filters Register tab by Email Store Data (Google Sheets) Append registration Tab: Register (gid=0) START (Schedule Trigger) Finds paid registrations Runs every 1 minute Get Rows (Google Sheets) Reads Register rows Reads full Register tab Filter Paid Not Sent (Filter) Finds rows with Payment Status=PAID & Email Sent=NO Filter node conditions Generate Ticket Data (Code) Generate ticket IDs & QR payloads Ticket ID format TL-YYYYMMDD-XXXX-N-HASH Generate QR Code (HTTP Request) Calls qrserver.com to build PNG URL: https://api.qrserver.com/v1/create-qr-code/?size=300x300&data= ... Build HTML Email (Code) Builds ticket HTML & embeds Base64 QR Template contains ticket details & QR Send Email (Gmail) Sends ticket email To: recipient Email; Subject configurable Update Sheet (Tickets) Append ticket rows Tab: Tickets (gid=2010454173) Parse Data (Code) Aggregates ticket IDs per email Updates Register with combined ticket IDs SCAN TICKET (Webhook) Check-in endpoint Path: /v1/scanner Parse Barcode (Code) Parses incoming scanner payload Expects JSON in body.barcode Get Tickets (Google Sheets) Lookup ticket by Ticket ID Filters Tickets tab by Ticket ID Ticket Available? (If) Validates existence & Checked In status Branches to update or return error Update Ticket Status (Google Sheets) Mark Checked In = YES Sets Checkin TIme to scannedAt Checked IN / Already Checked IN (RespondToWebhook) Respond payloads for scanner JSON responses with status & metadata Workflow Logic Registration: Writes to Register sheet. A scheduled job picks up PAID rows where Email Sent = NO; for each row it generates one record per ticket, calls the QR API for an image, sends an email per ticket (multi-ticket support), then appends Tickets rows and marks Email Sent = YES by updating the Register sheet with combined ticket IDs. Check-in: The scanner webhook accepts barcode JSON, extracts ticket_id, looks up the Tickets sheet, prevents duplicate check-ins by checking "Checked In" flag, and updates sheet with check-in timestamp on success. Customization Options Basic Adjustments Email Template: Edit Build HTML Email node to change branding, copy, or layout. Ticket ID Format: Change code in Generate Ticket Data to alter prefix or hash length. Event Metadata: Change event_name, event_date, event_location in code nodes. Advanced Enhancements Payment Gateway Integration: Integrate with payment gateway (e.g., webhook from Stripe) to automatically set Payment Status = PAID — complexity: medium. Cloud Storage for QR Images: Use cloud storage (S3) for QR images instead of base64-embedding — complexity: medium-high. Batch Email Provider: Use batch email provider (SendGrid/Mailgun) for high-volume events to reduce Gmail quota risks — complexity: medium. Troubleshooting Problem Cause Solution Invalid QR / scanner returns "Invalid QR code format" Scanner payload not sending barcode JSON or malformed JSON Ensure scanner POST body contains valid JSON string under body.barcode; validate payload in Parse Barcode node Ticket exists but cannot update Google Sheets API auth / permission error Reconnect Google Sheets OAuth2 credential; ensure the service account/user has edit access to the sheet Emails not sent Gmail OAuth2 credential missing or Gmail API quota reached Reauthorize Gmail credential; consider switching to SendGrid/Mailgun for large volumes Duplicate check-in allowed Logic checking "Checked In" value mismatch (case/format) Normalize the Checked In field values and use strict comparisons in Ticket Available? node Slow generation for many tickets Sequential QR calls and sends Use parallel execution or a dedicated email service; increase worker resources for n8n instance Use Case Examples Scenario 1: Community Fun Run (200 attendees) Challenge: Manual QR generation and emailing takes ~3 hours. Solution: After marking registrations as PAID, the scheduled job generates 200 QR tickets and emails them automatically. Result: Ticket prep completed in <5 minutes; volunteer time reduced by ~3 hours. Scenario 2: Regional Festival (2,000 tickets) Challenge: High volume requires reliable delivery and check-in speed. Solution: Use this workflow but replace Gmail with a transactional email provider (SendGrid) and host n8n on a scalable instance. Monitor Google Sheets and email provider quotas. Result: Automated delivery scales; on-site check-in handled via the /v1/scanner endpoint with near-instant validation. Additional Information Created by: Khmuhtadin Category: Event Automation, Ticketing Backend Tags: google-sheets , gmail , qr-code , webhook , ticketing Need custom workflows or help adapting this for your event? Contact us Note: Import the JSON into your n8n instance to get started. My Social: Threads LinkedIn Medium Workflow Collections portfolio