Realtime
Supabase Realtime is a WebSocket-based service that synchronizes client state globally, enabling developers to build modern web and mobile applications with live data updates.
Publisher review
Supabase Realtime is a WebSocket-based service that synchronizes client state globally, enabling developers to build modern web and mobile applications with live data updates. It is part of the Supabase ecosystem, an open-source Firebase alternative founded in 2020, and targets developers who need real-time features like chat, collaborative editing, or live dashboards without managing their own infrastructure. The service is designed for hobbyists and small teams on the Free plan, scaling to production workloads with the Pro plan and beyond, though it requires careful cost planning for larger projects.
Realtime offers three core capabilities: Broadcast, Presence, and Postgres Changes. Broadcast sends low-latency messages between clients on the same channel, but order is only guaranteed if a single publisher processes data serially—multiple publishers globally may see out-of-order delivery. Presence tracks and synchronizes online user state across clients, useful for showing who is active. Postgres Changes listens to database inserts, updates, and deletes, pushing changes to subscribed clients in real-time. The Free plan supports up to 500 connections and 5 GB egress, while the Pro plan allows up to 5,000 connections and 250 GB egress, with additional usage billed at $2.50 per 1 million messages and $10 per 1,000 peak connections over quotas.
Compared to competitors like Convex, Supabase Realtime offers a more predictable pricing model with transparent overage policies, but it can be expensive for large-scale applications. For instance, Convex provides 1 million monthly active users for $25, while Supabase's Pro plan starts at $25 for 100,000 MAUs, with overage costs of $0.00325 per MAU. Users on Reddit have noted that Realtime's pricing for 500 connections at $25/month, plus $10 per additional 1,000 connections, feels costly versus serverless alternatives like Upstash. However, Supabase's open-source nature and integration with PostgreSQL give it an edge for teams already using the database.
Honest trade-offs include limited consistency guarantees: Realtime data is not consistently delivered over the same channel, which can break applications requiring strict ordering. The Free plan's 500 connections and 5 GB egress are generous for prototypes but insufficient for production apps with moderate traffic. Scaling horizontally is tied to PostgreSQL instance performance, meaning you must upgrade compute resources (e.g., from Micro at $10/month for 1 GB RAM to 16XL at $3,730/month for 256 GB RAM) as user load grows, which can become expensive. Additionally, Broadcast's ordering guarantee only holds with serial publishers, making it unsuitable for globally distributed systems without custom workarounds.
How it works
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Broadcast messaging
Send low-latency messages between clients on the same channel, with ordering guaranteed only for serial publishers.
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Presence tracking
Store and synchronize online user state across clients, enabling features like live user lists and activity indicators.
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Postgres Changes listening
Listen to database inserts, updates, and deletes in real-time, pushing changes to subscribed clients via WebSockets.
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Global WebSocket sync
Sync client state globally over WebSockets, supporting up to 500 connections on Free and 5,000 on Pro plans.
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Open-source codebase
The Realtime server is open-source, allowing self-hosting or customization, though managed service is recommended for most users.
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Transparent overage pricing
Overage costs are clearly defined: $2.50 per 1 million messages and $10 per 1,000 peak connections beyond plan quotas.
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PostgreSQL integration
Tightly integrated with Supabase's PostgreSQL backend, enabling real-time data sync without additional middleware.
Strengths and trade-offs
Strengths
- Free plan supports 50,000 monthly active users and 500 connections, ideal for hobby projects and small teams starting out.
- Predictable pricing with transparent overage policies at $2.50 per 1 million messages and $10 per 1,000 peak connections.
- Open-source project allows full code inspection and self-hosting, giving developers control over deployment and customization.
- Reliable performance reported by users, with one developer noting it has been 'pretty reliable' for their production application.
Trade-offs
- Broadcast ordering is only guaranteed with serial publishers; multiple publishers globally can cause out-of-order message delivery.
- Pricing can be expensive for larger projects, with Pro plan at $25/month for 500 connections plus $10 per additional 1,000 connections.
- Realtime data is not consistently delivered over the same channel, limiting consistency guarantees for state synchronization.
- Scaling requires upgrading PostgreSQL compute instances (e.g., from $10/month Micro to $3,730/month 16XL), increasing costs significantly.
Pricing context
Free plan: $0/month for 50,000 MAUs, 500 connections, 5 GB egress. Pro plan: $25/month for 100,000 MAUs, 500 connections, 250 GB egress, with overage at $2.50 per 1M messages and $10 per 1,000 peak connections. Team plan: $599/month. Enterprise: custom pricing.
Getting started with Realtime
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Sign up for Supabase
Go to supabase.com and create a free account. Choose the Free plan to start with 500 connections and 5 GB egress, which is sufficient for prototyping and small projects.
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Create a new project
In the Supabase dashboard, click 'New project'. Enter a name and set a database password. Select a region close to your users. Wait a few minutes for the project to provision.
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Enable Realtime in settings
Navigate to the 'Realtime' section in your project dashboard. Toggle on 'Enable Realtime' for your database tables. You can also configure replication for specific tables to listen to changes.
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Subscribe to a channel
Install the Supabase client library in your app (e.g., `npm install @supabase/supabase-js`). Use `supabase.channel('my-channel')` to subscribe and listen for broadcast, presence, or Postgres Changes events.
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Test with a live update
Insert a row into a table you enabled Realtime on. In your client code, log the received payload to verify the update appears instantly. This confirms your real-time sync is working.
Frequently Asked Questions
What is Supabase Realtime and how does it work?
Supabase Realtime is a WebSocket-based service that synchronizes client state globally, enabling live data updates for apps. It offers Broadcast, Presence, and Postgres Changes capabilities, and is part of the open-source Supabase ecosystem, an alternative to Firebase.
What are the main features of Supabase Realtime?
Supabase Realtime has three core features: Broadcast for low-latency messaging, Presence for tracking online user state, and Postgres Changes for listening to database changes. It also provides global WebSocket sync, open-source code, and transparent overage pricing.
How much does Supabase Realtime cost and what are the plan limits?
The Free plan costs $0/month with 50,000 MAUs, 500 connections, and 5 GB egress. The Pro plan is $25/month for 100,000 MAUs, 500 connections, and 250 GB egress. Overage costs $2.50 per 1 million messages and $10 per 1,000 peak connections.
What are the limitations of Supabase Realtime's broadcast ordering?
Broadcast ordering is only guaranteed if a single publisher processes data serially. With multiple publishers globally, messages may arrive out of order. This makes it unsuitable for applications requiring strict ordering without custom workarounds.
How does Supabase Realtime pricing compare to Convex?
Supabase Realtime's Pro plan starts at $25/month for 100,000 MAUs, with overage at $0.00325 per MAU. Convex offers 1 million monthly active users for $25. For large-scale apps, Supabase can be more expensive, but its pricing is transparent.
How does scaling work with Supabase Realtime?
Scaling Realtime requires upgrading PostgreSQL compute resources, from a Micro instance at $10/month for 1 GB RAM to a 16XL at $3,730/month for 256 GB RAM. This ties horizontal scaling to database performance, increasing costs as user load grows.
Alternatives
How Realtime compares
Direct head-to-head against 3 competitors. Picked by 7wData.
Realtime
- Pricing
- Free plan: $0/month for 50,000 MAUs, 500 connections, 5 GB egress. Pro plan: $25/month for 100,000 MAUs, 500 connections, 250 GB egress, with overage at $2.50 per 1M messages and $10 per 1,000 peak connections. Team plan: $599/month. Enterprise: custom pricing.
- Target
- Supabase Realtime is a WebSocket-based service that synchronizes client state globally, enabling developers to build modern web and mobile applications with live data updates.
- Strength
- Free plan supports 50,000 monthly active users and 500 connections, ideal for hobby projects and small teams starting out.
- Watch for
- Broadcast ordering is only guaranteed with serial publishers; multiple publishers globally can cause out-of-order message delivery.
Inworld
- Pricing
- Custom/Contact sales
- Target
- Developers needing modular voice AI
- Deployment
- API
- Strength
- 200+ LLM integrations
- Watch for
- Enterprise-focused pricing
Google Gemini 3.1 Flash Live
- Pricing
- $0.60/m input, $2.40/m output tokens
- Target
- Cloud-native voice apps
- Deployment
- Google Cloud
- Strength
- Native audio processing
- Watch for
- Vendor lock-in
xAI Grok Voice Agent
- Pricing
- Custom/Contact sales
- Target
- High-scale conversational AI
- Deployment
- API
- Strength
- Low-latency responses
- Watch for
- Early-stage product
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Sources
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