Circle

Circle is community platform software built for creators — think of it as a more polished, purpose-built alternative to running a community on a general chat app. It supports discussion spaces, events, courses, and paid membership, all under your own branding rather than inside someone else's app.

For a newsletter, it's usually a step taken once the audience is engaged enough to want to talk to each other, not just read — a paid tier that includes community access is a common way newsletters extend beyond the email itself and give subscribers a reason to stick around between issues.