An Open Channel is a public channel that anyone can freely enter and exit. Think of it as a large chat stream, like the one in Twitch or Youtube live. For a ordinary chatroom, we recommend around 2000 concurrent users per channel, or else the conversation becomes too fast to follow.
However, we do support over 50,000+ concurrent users for cases such as live video-streaming chats, and control the message flow with technologies such as smart throttling and auto-partitioning. If you wish to use these features, contact us at firstname.lastname@example.org.
A Group Channel is a private chat that is enterable by invitation only. A 1-to-1 chat, a group chat with 12 friends, or an organization-wide chat with a few hundred members are all potential use cases of Group Channels.We recommend a max. of 250 to 300 users per channel, since the read-receipts and typing indicators becomes more of a noise for private chats once the users go beyond this number. It is ideal to keep it in the low two-digits range for an optimal chat experience.
More articles can be found @ SendBird HelpCenter