Convex vs Supabase vs Firebase for Real-Time (2026)

Building an app with live, reactive data? The three main contenders are Convex, Supabase, and Firebase. Each handles real-time differently. Firebase pioneered real-time sync. Supabase bolted it onto Postgres. Convex built the entire platform around reactivity. Here's how they compare for real-time use cases in 2026.

Quick Verdict

• Convex — Best native reactivity, most elegant real-time DX
• Firebase — Most mature real-time, best offline sync
• Supabase — Best for teams who want Postgres with some real-time features

How Real-Time Works in Each

Convex

Reactivity is the core architecture. Queries are functions that automatically re-run when their underlying data changes. Your UI subscribes to query results and updates instantly. No manual subscription management — it just works.

// This automatically updates when todos change
const todos = useQuery(api.todos.list)

Every query is reactive by default. Mutations trigger re-computation of affected queries. It's like having a spreadsheet for your backend.

Firebase

Firestore's onSnapshot and Realtime Database's on methods let you listen to document/collection changes. You manage subscriptions explicitly. Offline persistence syncs changes when connectivity returns.

onSnapshot(collection(db, "todos"), (snapshot) => {
  // Handle updates
})

Battle-tested at massive scale. Offline support is the best in class.

Supabase

Real-time via Postgres CDC (change data capture). Subscribe to INSERT, UPDATE, DELETE events on tables. Built on Phoenix channels (Elixir).

supabase.channel('todos')
  .on('postgres_changes', { event: '*', schema: 'public', table: 'todos' }, handler)
  .subscribe()

You get database change events, not reactive query results. There's a meaningful difference — you're notified of changes and must reconcile state yourself.

Reactivity Model Comparison

Feature	Convex	Firebase	Supabase
Reactive queries	✅ Native	❌ Manual subscriptions	❌ Change events
Automatic UI updates	✅	Manual	Manual
Offline support	✅ (optimistic updates)	✅ (best in class)	❌ Limited
Conflict resolution	Server authority	Last-write-wins	Server authority
Subscription granularity	Query-level	Document/collection	Table/row-level

Winner: Convex for developer experience. Firebase for offline and maturity.

Database Model

• Convex: Document database with relational capabilities. Schema validation with TypeScript. Supports references between tables.
• Firebase: NoSQL document database (Firestore) or JSON tree (Realtime Database). Denormalize everything.
• Supabase: Full PostgreSQL. SQL, joins, foreign keys, extensions. Most powerful query engine.

Winner: Supabase for query power. Convex for the best balance of structure and flexibility.

Type Safety

• Convex: End-to-end TypeScript. Schema defines types that flow through queries, mutations, and client hooks. If it compiles, it works.
• Firebase: TypeScript support via converters and generics. Not native — requires manual type definitions.
• Supabase: Generated TypeScript types from your database schema. Good but requires regeneration when schema changes.

Winner: Convex. Type safety is first-class, not bolted on.

Server Functions

Convex

All backend logic runs in Convex functions (queries, mutations, actions). Serverless, auto-scaling, transactional. ACID transactions across multiple documents. Scheduled functions built in.

Firebase

Cloud Functions for Firebase. Serverless but separate from the database layer. Transactions available in Firestore but more limited than Convex.

Supabase

Edge Functions (Deno) or database functions (PL/pgSQL). PostgreSQL transactions are robust. Edge Functions are separate from the database.

Winner: Convex for integration between logic and data. Supabase for raw transaction power (Postgres).

Pricing for Real-Time

	Convex	Firebase	Supabase
Free tier real-time	Included	50K reads/day (Spark)	Included (limited connections)
Scaling cost	Function calls	Per read/write/delete	Connection-based
Cost predictability	Good	Poor (read-heavy = expensive)	Good

Firebase's per-read pricing makes real-time expensive. Every listener that fires counts as a read. Convex and Supabase have more predictable pricing.

Performance & Scale

• Firebase: Proven at Google scale. Handles millions of concurrent connections. The most battle-tested option.
• Convex: Designed for performance. Incremental query re-computation is efficient. Scaling limits are less documented (newer platform).
• Supabase: Postgres performance for queries. Real-time throughput depends on your instance size and connection limits.

Winner: Firebase for proven scale. Convex for efficient reactivity.

When to Use Each

Choose Convex When

• Reactive UIs are core to your app (collaborative tools, dashboards, chat)
• You want the best DX for real-time features
• End-to-end TypeScript matters
• You want serverless functions integrated with your database
• Building a new project (greenfield)

Choose Firebase When

• Offline-first is critical (mobile apps, field workers)
• You need proven scale for millions of users
• Mobile-first development (iOS/Android SDKs are excellent)
• Already in Google Cloud ecosystem
• You need the largest community and most examples

Choose Supabase When

• You need SQL and Postgres features
• Real-time is nice-to-have, not the core feature
• You want row-level security and complex queries
• You need pgvector for AI features
• You want an open-source backend

FAQ

Is Convex production-ready?

Yes. Convex has been generally available since 2023 and is used by production apps. The team includes ex-Dropbox engineers who built their sync engine.

Can Supabase handle real-time chat?

Technically yes, but it's not ideal. You get change events, not reactive queries. For a chat app, Convex or Firebase provide better DX.

What about latency?

Convex and Firebase are optimized for low-latency real-time. Supabase real-time adds ~100-200ms for change propagation depending on load.

Can I self-host any of these?

Supabase: yes (Docker). Convex: no (cloud only). Firebase: no (Google only).

Which is cheapest for real-time heavy apps?

Convex or Supabase. Firebase's per-read pricing makes real-time expensive at scale.

Bottom Line

Convex offers the best real-time developer experience in 2026. Reactive queries that automatically update your UI are genuinely elegant. Firebase is the most proven option with unmatched offline support. Supabase is the right choice when you need Postgres power and real-time is secondary.

For a new real-time-first app: Convex. For mobile with offline: Firebase. For SQL-first with some real-time: Supabase.