Policr Mini: gatekeeper bot

Anyone who has run a public group knows the pattern: by evening there are dozens of "members" posting links and vanishing. Policr Mini cuts them off at the door by making every newcomer pass a check before they can write. 🚪

It is an open-source verification bot. The interface and description are in Chinese, but group setup runs on buttons and a console built as a Mini App.

What a newcomer's check looks like

When someone joins the group, the bot restricts their rights and asks them to pass a test. Pass it and the restrictions are lifted. Fail it and the member can be removed from the chat.

There are several kinds of checks. You can configure custom questions, and an update from early 2024 added grid verification: the bot builds one image of nine cells and asks the user to pick a category of pictures. The authors consider this noticeably stronger than a simple captcha, because there are more possible answers.

What the bot can do

• Different group types. Works in public and private groups, and where admins are anonymous.
• Custom checks. An admin can write their own questions instead of using only a ready template.
• Mini App console. Group settings are changed in a convenient panel inside Telegram.
• Open code. The project is written in Elixir under the MIT license, and you can deploy your own copy.

Commands worth knowing

1. /ping. Quickly checks that the bot is alive.
2. /sync. Refreshes data about a group or user (for example after a rename).
3. /embarrass_member. Manually starts a check on a specific member. It is marked experimental.
4. /sponsorship. Shows how to support the project.

The old panel login commands (/login and /console) are deprecated. The Mini App replaces them, and owners get /admin_v2.

Hosted bot or your own server

The easiest path is the hosted version: add the bot to your group and configure it. You can also run a copy yourself, for example in Docker with a PostgreSQL database.

Your own server gives control over data but costs time for setup and updates. For a small group the ready-made bot is usually enough. 🛠️

Setup tips

• Admin rights. Give the bot rights to restrict members and delete messages.
• Answer time. Do not set the timer too short: a real person may get distracted.
• Question language. If your group is not Chinese-speaking, choose checks your members understand, such as picture-based ones.
• Test with a spare account. See how it looks through a newcomer's eyes.

The bot has about 25 thousand users, and its open project has collected over a thousand stars on the developer platform. For a moderation tool that visibility helps: bugs in open code get found faster. ⭐

Remember that any check reduces the flow of newcomers. In a small group, protection that is too strict can scare off real people before it stops spammers.