Captcha in a Telegram group: protection or a door that scares people off
Types of entry checks, what they actually stop, and how not to turn joining a chat into an exam.
An entry check stops bots before the first message. It also scares off some real people who came to read. The question is balance.
What a captcha stops
Mass spam accounts follow a script: join, drop a link, leave. Any check breaks that scenario because it requires an action the script does not have.
Targeted spam from a real person is not stopped by a captcha — filters and a newcomer sandbox handle that.
Kinds of checks
An “I am not a bot” button. One tap. Stops primitive scripts and barely bothers people. A sensible default.
A small maths problem. “What is 7 + 4?” Breaks scripts more reliably but demands attention — some people quietly leave.
A check before joining. The request is approved after an action. The strictest option: suitable for closed communities, wrong for open support chats.
Settings people forget
Timeout. If the check is not passed within N minutes, the person should be removed (with the ability to return), otherwise the member list fills up with silent accounts.
Silence until passing. Before passing, the member should not be able to write — otherwise the point is lost.
The notice. The verification message should delete itself instead of hanging in the chat forever.
When you do not need one
For a small chat of friends or a comment section with almost no spam a captcha only gets in the way. Start with filters and a sandbox, add the check when spam appears.
See how it is configured here on the moderation page.