@doublegram_captcha_bot is Doublegram's anti-spam Telegram bot for groups and supergroups. It blocks bot raids before they can post: every new member is muted on join, asked to verify through a Telegram Mini App with Google reCAPTCHA, and removed automatically if they do not finish within your configured timeout.
Add @doublegram_captcha_bot as a group administrator with Restrict members permission — after that, verification runs on its own for each new join.
What happens when someone joins?
- The bot mutes the new member (no messages, media, polls, or links).
- A welcome message appears with a Verify Captcha button.
- The member opens the Mini App and completes reCAPTCHA.
- On success, the bot unmutes them and updates the group message.
- If they never verify, a background process kicks or bans them after the timeout.
Protection layers
- reCAPTCHA — human check (invisible or checkbox based on risk profile)
- Geographic firewall — block or allow countries before captcha loads (
/firewall) - Cross-group trust — users verified in other Captcha groups can skip repeat checks
- Progressive challenge — riskier profiles get a harder captcha
Supergroups recommended: Captcha is built for supergroups. Basic groups may have limited Telegram API support — the bot warns you if added to a regular group.
Admin commands (in the group)
/settings— timeout, silent mode, trust, notifications, language/firewall— geographic rules/stats— verification metrics/captcha— force verification on a user (reply required)/debug— permissions and setup diagnostics
Quick reference
- Bot: @doublegram_captcha_bot
- Chat type: groups and supergroups
- Required permission: Restrict members
Related: add the bot to your Telegram group with the right admin rights — see Add @doublegram_captcha_bot to Your Telegram Group.