Stream privacy settings

Streams are similar to chatrooms, IRC channels, or email lists in that they determine who receives a message. There are three types of streams in Zulip.

• Public: Members can join and view the complete message history. Public streams are visible to Guest users only if they are subscribed (exactly like private streams with shared history).

• Private, shared history: You must be added by a member of the stream. The complete message history is available as soon as you are added.

• Private, protected history: You must be added by a member of the stream. You only have access to the messages that are sent after you are added.

Privacy model for private streams

At a high level:

• Organization owners and administrators can see and modify most aspects of a private stream, including the membership and estimated traffic. Owners and administrators generally cannot see private stream messages or do things that would give them access to private stream messages, like adding new subscribers or changing the stream privacy settings.

• Organization members and moderators cannot easily see which private streams exist, or interact with them in any way until they are added. Given a stream name, they can figure out whether a stream with that name exists, but cannot see any other details about the stream.

• From the perspective of a guest, all streams are private streams, and they additionally can't add other members to the streams they are subscribed to.

There are two situations in which an organization owner or administrator can access private stream messages:

• Via some types of data export.

• Owners and administrators can change the ownership of a bot. If a bot is subscribed to a private stream, then an administrator can get access to that stream by taking control of the bot, though the access will be limited to what the bot can do. (E.g. incoming webhook bots cannot read messages.)

Detailed permissions

Public streams

✔ Always

◾ If subscribed to the stream

✶ Configurable. Owners, Administrators, and Members can, by default, post to any public stream, and Guests can only post to public streams if they are subscribed.

Private streams

✔ Always

◾ If subscribed to the stream

✶ Configurable, but at minimum must be subscribed to the stream.

Related articles

• Roles and permissions
• Stream sending policy