Realtime subscriptions

Realtime subscriptions let an application listen to a database and be told immediately when something changes. A new row, an edit or a deletion is sent to every connected screen within moments. Think of a live order board in a kitchen, a chat window or a dashboard that updates without a page refresh. Supabase provides this on top of its database.

Without it, an app has to ask the server over and over whether anything is new, which wastes resources and still feels slow. With subscriptions, the data on screen stays current and shared screens stay in step. It makes products feel alive.

It matters when several people work on the same data at once or when stale information costs money, such as stock levels or live status. For a report that is read once a day, it is unnecessary. This is a developer feature, so it affects what your team can build rather than something you switch on.

• Which changes can be subscribed to: whole tables, single rows or filtered sets?
• How do access rules apply, so users only receive data they are allowed to see?
• What limits apply to concurrent connections and messages?
• What happens to updates when a user's connection drops and comes back?