MQTT.Agent - open protocol for AI agents

Spec
Platform Comparison

CloudSignal vs Supabase Realtime
Dedicated Broker vs Database-Attached

Supabase Realtime is excellent when your data already lives in Postgres and your real-time needs are modest. When messaging is the product, CloudSignal gives you a purpose-built broker with QoS guarantees and AI-native streaming.

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Feature-by-Feature Comparison

An honest side-by-side. We call out where Supabase has the stronger story.

Feature
CloudSignal
Supabase Realtime
Protocol
MQTT clients are portable. Supabase Realtime is tied to Phoenix Channels and the Supabase stack
MQTT (ISO/IEC 20922 open standard) over TCP or WebSockets
Phoenix Channels over WebSockets, plus Postgres logical replication
Primary purpose
Different products. Supabase is a backend platform with a realtime add-on. CloudSignal is realtime first
Purpose-built real-time messaging infrastructure
Realtime layer bundled on top of Postgres, Auth, and Storage
Delivery guarantees
If a client misses a broadcast during reconnect on Supabase, it is gone unless you read from Postgres
MQTT QoS 0, 1, and 2 for at-most-once, at-least-once, and exactly-once
Best-effort broadcast and presence, no QoS levels
Offline support
MQTT handles offline at the protocol layer. Supabase requires you to design catch-up around the database
Persistent sessions, retained messages, and QoS 1/2 queueing
No native offline queue. Reconnecting clients catch up via Postgres reads, not the realtime stream
Security model
Different models. Both work. Supabase RLS is powerful when your data already lives in Postgres
Broker-enforced ACL rule sets with identity-bound topics
Row-Level Security on Postgres tables plus channel-level auth
AI integration
Supabase has Edge Functions, but no MQTT-native AI streaming product
AI Transport for Vercel AI SDK with streaming and offline resume
No first-party AI streaming transport over realtime channels
Postgres integration
If your app is database-change-driven, Supabase is hard to beat
Connect via REST API bridge or webhooks
Native Postgres logical replication. Subscribe to table changes directly
Bundled services
Supabase is a one-stop backend. CloudSignal focuses on doing one thing well
Messaging, REST API bridge, and PWA push notifications
Postgres, Auth, Storage, Edge Functions, Vector, and Realtime in one platform
Scale of concurrent clients
For high-fanout pub/sub like notifications or live dashboards, a dedicated broker scales more cleanly
MQTT broker designed for high-fanout pub/sub
Realtime tier has per-project connection and message caps
Vendor lock-in
The Supabase Realtime API does not exist on any other platform
None. MQTT clients run unchanged on any broker
Postgres is portable, but Realtime, Auth, and Edge Functions are Supabase-specific

Where CloudSignal Pulls Ahead

Supabase Realtime is great when realtime is a side feature. CloudSignal is where teams land when realtime becomes the product itself.

Purpose-Built Realtime Infrastructure

Supabase Realtime is a real-time layer bolted onto a database product. CloudSignal is built ground-up as a messaging broker, with fanout, QoS, retained messages, and ACL rule sets as first-class primitives. When your real-time workload outgrows a database-attached channel, a dedicated broker is the cleaner answer.

Real Delivery Guarantees

Supabase broadcasts are best-effort. If a subscriber misses a message during a reconnect, the only way to catch up is to query the database again. CloudSignal supports MQTT QoS 0, 1, and 2 plus retained messages, so clients catch up automatically through the protocol itself.

AI Transport Out of the Box

CloudSignal ships AI Transport, a drop-in transport for the Vercel AI SDK that streams tokens over MQTT and resumes after disconnects. With Supabase you would assemble that streaming and resume layer yourself across Edge Functions, Realtime broadcasts, and database state.

Portable Across Brokers

Your Supabase Realtime client code only runs on Supabase. CloudSignal speaks MQTT, so the same clients work on any broker, open source or managed. If you ever need to migrate or self-host, your application code does not change.

How to Decide

You can absolutely run both side by side. CloudSignal for messaging, Supabase for data. The decision is which one owns your realtime path.

Choose CloudSignal when…

  • Your real-time workload is the product, not a database side-channel
  • You need delivery guarantees, retained state, and reliable reconnects
  • You want AI streaming over MQTT with offline resume out of the box
  • You want broker-enforced ACL rule sets with topic-pattern policies
  • You want to keep the option to migrate to any MQTT broker later

Choose Supabase Realtime when…

  • You are already using Supabase for database, auth, and storage
  • Your real-time needs are driven by Postgres row changes
  • Row-Level Security on tables is the security model you prefer
  • You want a single platform that covers backend, realtime, and edge
  • Your traffic fits inside Supabase's realtime connection and message caps
Realtime as the Product, Not a Side Channel.

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