How to set up a CAPTCHA for new subscribers

Setting up a CAPTCHA for new subscribers in your Telegram group or channel is done through specialized moderation bots like Combot, Shieldy, Captcha Bot, or Rose Bot. These bots challenge new members with a verification task — such as pressing a button, solving a math problem, or identifying images — to confirm they are real people and not spam bots. The process typically takes under 5 minutes to configure and can dramatically reduce spam by 90–99%.

Why You Need a CAPTCHA for New Subscribers

Telegram groups and channels with open join links are frequent targets for spam bots. These automated accounts flood chats with ads, phishing links, and scam messages within seconds of joining. A CAPTCHA system acts as a gatekeeper, requiring every new member to prove they are human before they can interact.

The Scale of the Problem

A group with 5,000+ members that lacks CAPTCHA protection can receive 50–200 spam messages per day. Bots join in waves, often coordinated to bypass simple anti-spam measures. Without verification, your admins spend hours manually banning accounts instead of managing content.

How CAPTCHA Bots Work

When a new user joins your group, the CAPTCHA bot automatically:

  1. Restricts the new member's ability to send messages
  2. Sends a verification challenge (button press, math puzzle, image selection)
  3. Waits for a response within a set time limit
  4. Grants full permissions if verified, or kicks/bans the user if they fail

Choosing the Right CAPTCHA Bot

Different bots offer different verification methods and features. Here are the most popular options:

Shieldy (@shaboroshka_bot)

  • Verification type: Button press or custom equation
  • Best for: Small to medium groups (up to 10,000 members)
  • Setup difficulty: Easy
  • Key feature: Lightweight, fast response time

Combot (@comaboroshka_bot)

  • Verification type: Button press with customizable text
  • Best for: Large groups (10,000–200,000 members)
  • Setup difficulty: Medium
  • Key feature: Advanced analytics and detailed member statistics

Rose Bot (@MissRose_bot)

  • Verification type: Button CAPTCHA, math CAPTCHA, text CAPTCHA
  • Best for: Groups of any size
  • Setup difficulty: Medium
  • Key feature: All-in-one moderation with welcome messages, filters, and notes

Captcha Bot (@Captcha_Robot)

  • Verification type: Image-based CAPTCHA, math equations, custom challenges
  • Best for: Groups needing strong protection against sophisticated bots
  • Setup difficulty: Easy to medium
  • Key feature: Multiple difficulty levels for different security needs

Step-by-Step Setup Guide (Using Shieldy)

Step 1: Add the Bot to Your Group

Open your Telegram group, tap the group name to access settings, select Add Members, and search for @shaboroshka_bot. Add it to the group.

Step 2: Grant Admin Permissions

The bot needs specific admin rights to function. Go to Group Settings → Administrators → Add Administrator, select the bot, and enable these permissions:

  • Delete messages — to remove the CAPTCHA prompt after verification
  • Ban users — to kick members who fail verification
  • Restrict members — to mute new joiners until they pass the challenge

Step 3: Configure CAPTCHA Settings

Send the following commands in the group chat or in a private message to the bot:

  • /captcha — toggle CAPTCHA on or off
  • /language — set the bot's language (supports English, Russian, and 20+ others)
  • /timeLimit — set how long users have to solve the challenge (default: 120 seconds)
  • /banNewcomers — choose whether failed users are kicked or banned permanently

Step 4: Choose the Verification Type

Use the /captchaType command to select your preferred challenge:

  • Simple button — user taps a single button to confirm they are human
  • Digits — user must enter a randomly generated number
  • Math — user solves a basic arithmetic problem (e.g., 7 + 3 = ?)

Step 5: Test the Configuration

Have a friend (or a secondary account) join the group to verify that:

  • The CAPTCHA message appears immediately
  • The new member cannot send messages before verification
  • Successful verification grants full message permissions
  • The CAPTCHA prompt is deleted after completion

Step-by-Step Setup Guide (Using Rose Bot)

Step 1: Add and Promote Rose Bot

Add @MissRose_bot to your group and promote it to admin with Delete messages, Ban users, and Restrict members permissions.

Step 2: Enable CAPTCHA Verification

Send this command in the group:

/captcha on

Step 3: Configure CAPTCHA Mode

Choose your preferred verification method:

/captchamode button

Available modes: button, math, text

Step 4: Set the Time Limit

Define how many seconds new members have to complete the challenge:

/captchatime 120

Step 5: Configure Failure Action

Decide what happens when a user fails to verify:

/captchakick on

This kicks unverified users after the time limit expires. They can rejoin and try again.

Advanced Configuration

Custom Welcome Messages with CAPTCHA

Many bots allow you to combine a welcome message with the CAPTCHA challenge. For example, in Rose Bot:

/setwelcome Hey {first}! Welcome to our community. Please complete the verification below to start chatting.

Whitelisting Trusted Users

If your group frequently receives new members who are invited by existing admins, you can configure some bots to skip CAPTCHA for users added directly by administrators. In Combot, this is available under Settings → Newcomers → Skip verification for invited users.

Setting Strictness Levels

For high-value groups (crypto communities, business groups), consider using image-based CAPTCHA or multi-step verification. Captcha Bot offers difficulty levels from 1 (simple button) to 4 (complex image recognition), configurable with /difficulty.

Channel-Linked Groups

If your Telegram channel has a linked discussion group, the CAPTCHA bot works on the group level. Channel subscribers who join the discussion group will still need to pass verification. This is relevant if you use services like tgchannel.space to showcase your channel content on the web — verified discussion groups signal quality and trust to potential subscribers browsing your channel's web presence.

Tips & Best Practices

  • Set a reasonable time limit: 60–120 seconds works well for most groups. Too short frustrates legitimate users on slow connections; too long gives bots time to adapt.
  • Start with button CAPTCHA: It is the most user-friendly option. Only escalate to math or image CAPTCHA if button verification proves insufficient against spam.
  • Enable auto-delete of service messages: Configure the bot to remove "User joined" and CAPTCHA messages after verification to keep the chat clean.
  • Combine CAPTCHA with slow mode: For groups under heavy attack, enable Telegram's built-in Slow Mode (Settings → Permissions → Slow Mode) alongside the CAPTCHA bot for layered protection.
  • Monitor the bot's performance: Check how many users pass vs. fail verification weekly. If the failure rate exceeds 30%, your CAPTCHA may be too difficult for legitimate users.
  • Keep the bot updated: Follow the bot's official channel for updates. Bot developers regularly patch bypasses that spam networks discover.

Common Mistakes

Mistake 1: Not granting sufficient admin permissions
Why it's wrong: The bot silently fails without Ban users or Restrict members permissions, and new members can post freely despite the CAPTCHA appearing.
How to avoid: Double-check all three required permissions (delete messages, ban users, restrict members) are enabled in the bot's admin settings.

Mistake 2: Setting the time limit too short
Why it's wrong: Users on older devices or slow networks may need 30+ seconds just to load the CAPTCHA. A 10-second limit leads to legitimate members being kicked repeatedly.
How to avoid: Use 60 seconds as the minimum. Monitor complaints and adjust upward if needed.

Mistake 3: Using multiple moderation bots simultaneously
Why it's wrong: Two bots both trying to restrict and verify the same new member creates conflicts — double CAPTCHA prompts, permission errors, or users getting kicked by one bot while being verified by another.
How to avoid: Choose one primary moderation bot and disable overlapping features in any secondary bots.

Mistake 4: Forgetting to test after setup
Why it's wrong: Configuration errors are invisible until a real user joins. A misconfigured bot may block everyone or let everyone through without challenge.
How to avoid: Always test with a secondary account or ask a friend to join the group after setup.

Mistake 5: Never updating the CAPTCHA type
Why it's wrong: Sophisticated spam networks adapt to specific CAPTCHA types over time. A button-only CAPTCHA may become ineffective after several months.
How to avoid: Review your spam logs monthly. If spam increases despite CAPTCHA being active, switch to a more challenging verification method.

Frequently Asked Questions

Does CAPTCHA work in Telegram channels or only in groups?
CAPTCHA bots only work in groups, not channels. Channels do not have a join verification mechanism. However, if your channel has a linked discussion group, you can protect that group with CAPTCHA to keep conversations spam-free.

Will the CAPTCHA bot affect existing members?
No. CAPTCHA verification only triggers for new members who join after the bot is activated. Existing members retain their permissions and are not asked to verify.

Can I customize the CAPTCHA message language?
Yes, most popular bots support 20+ languages. Use the /language command (Shieldy) or /captchalang (other bots) to set the language matching your audience. Some bots auto-detect the user's Telegram language setting.

What happens if a legitimate user fails the CAPTCHA?
By default, most bots kick (not ban) failed users, meaning they can rejoin and try again using the group's invite link. You can change this to a permanent ban if your group faces persistent attacks from the same accounts.

Is there a way to verify users without CAPTCHA?
Yes. Some groups use manual approval (Group Settings → Join Requests) where admins approve each member individually. This works for small, exclusive groups but does not scale beyond a few hundred join requests per day.