The most active Substack groups this week.

Each full UTC day, members who run the Subshack extension report privacy-safe totals for the group chats they belong to: messages, active participants, replies and help requests. A day counts only when three independent installations report the same group for that day. The day's score, from 0 to 100, weighs message volume most, then active participants, replies and the share of help requests. The 7-day score is the mean of the qualified days of the last seven, and groups are ranked by it. Today 126 of the 1,867 tracked groups are ranked.

A message that asks something: a question mark, or words such as "any advice", "can anyone", "how do I", "help", "feedback", "stuck" or "recommendation". The check runs in the member's browser and only the count leaves it, never the message.

A group appears as soon as one Subshack installation sees it, but its score stays hidden until three independent installations confirm the same complete UTC day. One or two installations are not enough to rule out a single member's view. A group that had no confirmed day in the last seven days shows as quiet this week.

The directory only knows the group chats that members running Subshack belong to. A group nobody in that set has joined is not observed yet, however active it is. You can nominate it with its chat address: it is listed when a first installation reports it.

A language model reads what a person would read before joining: the chat title, the publication tagline, the creator's bio, the titles of their latest posts and the topics seen in the chat. It picks one main category and up to two secondary ones from a fixed list, so a group can show under up to three categories. The choice is checked again every 30 days.

The list is fixed so that groups stay comparable from one week to the next: Writing & Growth, Business & Careers, Tech & AI, Finance, News & Politics, Culture & Ideas, Health & Wellbeing, Mindset & Spirituality, Lifestyle & Relationships, and Other. The model can only choose from it and cannot add a category. A category with no group is not offered as a filter, and on a computer the filters that do not fit on two lines are under More.

Other means no subject could be inferred: a chat named after a person with no tagline, no bio and no posts, or a personal diary with no theme. A group observed for the first time also starts in Other until it is classified, usually within a few hours.

Daily totals and topic labels per group, plus the group's public identity (name, logo, member count, publication and chat link). No message text and no member name or identity is stored or shown.

Totals arrive once a UTC day is complete, and this page refreshes every hour. A group's rank can therefore move once a day, and the 7-day window moves with it.

Yes. A group page can be claimed by its admin: we check the publication address by hand before adding the Verified admin badge. To report a wrong category or a wrong listing, use the feedback link at the bottom of the directory.