Loop - Messenger with AI Chatbot
Loop is a cross-platform messaging app built with Flutter and Firebase, with real-time one-to-one and group chat plus an integrated AI chatbot. One Dart codebase targets Android, iOS and web, with Firebase handling auth, message persistence and live delivery.
- Role
- Sole developer — Flutter client, Firebase data model and AI integration.
- Year
- 2024
- Stack
- Flutter, Firebase, Web socket, Dart
The problem
Building a messenger separately for Android, iOS and web triples the surface area for a feature set that is identical on all three. The interesting problems in chat — delivery state, ordering, offline behaviour — are platform-independent, so the platform-specific work is pure overhead.
How it was built
01Real-time message delivery
Messages stream through Firebase listeners so participants see them without polling. The subtle part is ordering and delivery state: a message must appear immediately for the sender, reconcile against the server's timestamp, and show honestly whether it has actually been delivered.
02Group chat semantics
Group membership, per-member read state and message fan-out are modelled explicitly. Read receipts across many participants are a per-member relation, not a flag on the message — getting that wrong makes unread counts drift, which erodes trust in the whole interface.
03AI chatbot as a participant
The assistant is modelled as another participant in a conversation rather than a separate mode. The chat surface, history and delivery path are the same, so there is no second UI to maintain and no context switch for the user.
04Offline and reconnect behaviour
Sent messages queue locally and reconcile on reconnect. Mobile networks drop constantly; a messenger that loses a message on a tunnel is not usable, so the local write is the source of truth until the server confirms.
Stack decisions
Why each piece was chosen, rather than just what was used.
Flutter
One Dart codebase across Android, iOS and web, with genuinely consistent rendering because Flutter draws its own widgets rather than wrapping platform controls. For a UI-heavy app with identical behaviour everywhere, that consistency is the point.
Firebase
Real-time listeners, auth and persistence without operating a socket layer. For a chat product this collapses most of the backend into configuration, leaving the effort for the client-side delivery semantics that actually differentiate it.
WebSocket
Persistent connections for live delivery, so messages push rather than being polled for.
What it does
- Real-time one-to-one and group messaging
- Integrated AI chatbot as a conversation participant
- Per-member read state and unread counts
- Offline queueing with reconnect reconciliation
- Single codebase across Android, iOS and web
Questions this raises
Is Flutter a reasonable choice for a real-time chat app?
Yes, and for this class of app it is a strong one. Chat is UI-dense with identical behaviour on every platform, which is exactly where a single codebase pays off. Flutter draws its own widgets, so the interface is genuinely consistent rather than approximately consistent, and Firebase's Dart SDK makes real-time listeners straightforward.
How should read receipts be modelled in group chat?
As a per-member relation, not a boolean on the message. A message read by three of eight participants has no single read state. Storing it on the message forces a lossy choice and makes unread counts drift over time, which quietly destroys confidence in every badge in the app.
Related work
Building something similar?
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