Supabase
Supabase has added Broadcast Replay to its Realtime service, a feature that lets clients automatically retrieve messages they missed during a connection interruption rather than losing them entirely.
The feature was announced on LinkedIn with a focus on live event use cases -- sports apps, concert platforms, and anywhere users are watching something unfold in real time. If a connection drops and recovers, Broadcast Replay picks up where it left off instead of leaving a gap in the event stream.
The Problem It Solves
Real-time messaging over WebSockets is inherently stateless from the client's perspective. When a connection drops, the client reconnects and rejoins the channel, but any messages broadcast during the outage are gone. For many apps -- chat, collaborative editing, live dashboards -- this is tolerable. For others, those gaps are a real problem.
Consider a live sports app tracking play-by-play events. A user on a shaky mobile connection drops out for 20 seconds during a key moment. Without replay, they rejoin mid-stream with no context for what happened. With Broadcast Replay, the client catches up automatically on reconnect.
The same logic applies to trading tools, logistics tracking, or any application where the sequence of events matters, not just the current state.
How It Fits into Supabase Realtime
Supabase Realtime already supports three core features: Broadcast (one-to-many messaging across clients on a channel), Presence (tracking which users are online), and Postgres Changes (streaming database change events). Broadcast Replay extends the first of those, adding a persistence layer so recent messages can be retrieved on reconnect.
This is a meaningful quality-of-life improvement for developers building on Realtime who previously had to implement their own catch-up logic -- typically involving storing messages in the database and fetching them manually on reconnect. Broadcast Replay handles that plumbing automatically.
For small teams and solo builders shipping apps with Supabase, one fewer infrastructure problem to solve is significant. The feature is available now and documented in the Supabase Realtime docs.
Sources
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