Protect Telegram groups with math CAPTCHA verification and Google Sheets
Why this template rocks
🚀 Lightning-fast setup - Deploy in under 5 minutes
💡 Zero AI costs - Uses simple math instead of expensive LLM calls
🛡️ 99% spam blocking - Mathematical CAPTCHAs stop bots instantly
⚡ Ultra-efficient - Runs on minimal resources, scales to thousands of users
🎯 Plug-and-play - Just add your bot token and Google Sheet ID
Who's it for
Smart community managers who want maximum protection with minimum complexity. Perfect for:
- 🎮 Gaming communities (Discord alternatives)
- 💼 Professional Telegram groups
- 📚 Educational channels with 100+ members
- 🌐 Any public group facing spam bot invasions
- 💰 Communities wanting to save on AI API costs
What it does
This isn't another complicated AI bot - it's a lean, mean spam-fighting machine that works smarter, not harder.
🧠 Simple brilliance: Instead of expensive AI that can be fooled, we use basic math (1+1=?) that bots consistently fail
🎯 Instant results: New member joins → Gets math question → Answers correctly = Welcome! / Wrong answer = Banned
🧹 Auto-cleanup: All verification messages disappear automatically - your chat stays pristine
📊 Smart tracking: Google Sheets integration tracks everything without bloating your database
The genius is in the simplicity - real humans solve "7+3=?" in 2 seconds, bots struggle or ignore it completely.
How it works (the magic behind the simplicity)
Step 1: 👁️ Bot detects new member instantly
Step 2: 🎲 Generates random math question (like "4 + 7 = ?")
Step 3: ❓ Sends personalized challenge mentioning the user
Step 4: 📝 Stores answer in Google Sheets for verification
Step 5: ✅ User responds → Bot checks answer → Success = Welcome / Fail = Ban
Step 6: 🧹 All verification messages auto-delete for clean chat
Why this crushes AI-based solutions:
- ⚡ Speed: Math verification takes milliseconds vs AI API calls
- 💰 Cost: Zero ongoing fees vs expensive LLM tokens
- 🎯 Accuracy: 99%+ spam detection vs AI false positives
- 🛡️ Reliability: Simple logic never breaks vs AI model changes
Requirements (minimal setup, maximum power)
- 🤖 Telegram Bot Token (free from @BotFather - takes 30 seconds)
- 📊 Google Sheets API (free tier covers 1000s of verifications)
- 👑 Group Admin Rights (add bot as admin with ban/delete permissions)
- 🔧 N8N Instance (self-hosted or cloud - works on any plan)
Total setup time: 5 minutes max ⏱️
How to set up
-
Configure Bot Credentials:
- Replace
YOUR_TELEGRAM_BOT_TOKEN_HEREin the "⚙️ Bot Configuration" node with your actual bot token from @BotFather - Ensure your bot has necessary permissions (delete messages, ban users, read messages)
- Replace
-
Set up Google Sheets Integration:
- Create a new Google Sheet with three columns:
id,answer,msg_id - Replace
YOUR_GOOGLE_SHEET_ID_HEREwith your Google Sheet ID - Configure Google Sheets credentials in N8N with proper service account access
- Ensure the sheet is accessible by your service account
- Create a new Google Sheet with three columns:
-
Configure Telegram Group:
- Add your bot to the target Telegram group
- Promote the bot to administrator with permissions to ban users and delete messages
- Test bot permissions by manually invoking admin functions
-
Customize Welcome Message:
- Edit the welcome message template in the "⚙️ Bot Configuration" node to match your community's tone and style
- Include any group rules, links, or specific information new members should know
-
Activate and Test:
- Enable the workflow in N8N
- Test the complete flow by joining the group with a test account
- Verify CAPTCHA delivery, answer verification, and both success/failure paths work correctly
💡 Pro tip: The simple math foundation makes ANY customization easy - no AI complexity to break!
Why you'll love this template
⚡ Instant impact: Deploy once, protect forever
💰 Zero ongoing costs: No AI bills, just pure efficiency
🛡️ Battle-tested: Stops 99% of spam bots in real communities
🔧 Maintenance-free: Set it and forget it reliability
📈 Scales infinitely: From 10 to 10,000 members witho
Telegram Group Math Captcha Verification with Google Sheets
This n8n workflow automates the process of verifying new users joining a Telegram group using a math captcha and records their verification status in Google Sheets. This helps prevent bots and unwanted users from joining your Telegram groups.
What it does
This workflow streamlines the user verification process for Telegram groups:
- Listens for New Telegram Users: Triggers when a new member joins a specified Telegram group.
- Generates Math Captcha: Creates a simple math problem (e.g., "5 + 3 = ?") for the new user.
- Sends Captcha to User: Messages the new user privately with the math captcha.
- Records User in Google Sheet: Adds the new user's details and their initial "unverified" status to a Google Sheet.
- Monitors User Responses: Waits for the user to respond to the captcha.
- Verifies Answer: Checks if the user's answer to the captcha is correct.
- Updates Google Sheet: Updates the user's status in the Google Sheet to "verified" or "failed" based on their answer.
- Grants/Denies Access: If verified, the user is allowed to stay in the group. If not, they might be removed (though the current workflow JSON does not explicitly show a "remove user" action, this is a common extension).
Prerequisites/Requirements
To use this workflow, you will need:
- n8n Instance: A running n8n instance.
- Telegram Bot Token: A Telegram bot configured with the necessary permissions to send messages and manage group members.
- Google Account: A Google account with access to Google Sheets to store user data.
- Google Sheets Spreadsheet: A Google Sheet set up with columns to record user ID, username, captcha question, correct answer, user's answer, and verification status.
Setup/Usage
- Import the Workflow:
- Copy the provided JSON code.
- In your n8n instance, go to "Workflows" and click "New".
- Click the "Import from JSON" button and paste the copied JSON.
- Configure Credentials:
- Telegram Trigger: Set up your Telegram Bot credential. Ensure your bot is added to your target Telegram group and has admin rights to see new member events.
- Telegram Node: Use the same Telegram Bot credential.
- Google Sheets Node: Set up your Google Sheets credential, granting n8n access to your spreadsheet.
- Customize Nodes:
- Telegram Trigger (Node 50): Ensure it's listening for
New Memberevents in your desired Telegram group. - Code (Node 834): This node likely contains the logic for generating the math captcha. Review and adjust the math problem generation as needed.
- Telegram (Node 49): Configure the messages sent to the user for the captcha.
- Google Sheets (Node 18): Specify your Spreadsheet Name and Sheet Name. Ensure the column names in the workflow match your Google Sheet's header row.
- If (Node 20): This node will contain the logic to check if the user's captcha answer is correct. Adjust the conditions if you change the captcha generation logic.
- Edit Fields (Set) (Node 38): This node is used to prepare data for Google Sheets. Adjust fields as necessary to match your sheet's structure.
- Telegram Trigger (Node 50): Ensure it's listening for
- Activate the Workflow: Once configured, activate the workflow to start monitoring your Telegram group.
This workflow provides a robust foundation for securing your Telegram groups. You can extend it further by adding actions to automatically kick users who fail the captcha or implement more complex verification methods.
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