Deborah Ruck

5 days ago

Top 5 Real-Time Databases Compared

Wondering which real-time database is right for your app? Some excel at rapid prototyping, others shine for production apps, and a few are built specifically for niche use cases like mobile-first or time-series data.

Here’s a breakdown of the top platforms: what they’re best at, where they fall short, and when to reach for each one.

1. Convex

Type: Reactive database with built-in dependency tracking. When data changes in the backend, the affected queries re-run automatically and updates are pushed to the client.

Best for: Convex is best for full-stack JavaScript/TypeScript teams building collaborative UIs, real-time dashboards, or multiplayer tools with shared state and strong consistency..

Why it stands out:

• TypeScript end-to-end: same language for backend logic and frontend queries
• Built-in reactive queries re-run automatically when data changes
• WebSocket-based sync with built-in dependency tracking
• ACID-compliant transactions for consistency, even in multi-user environments
• Fully managed, built-in scaling, validation, scheduling, and caching

Use it when:

• You're building with React or Next.js
• You want real-time UIs without writing sync logic
• Correctness matters. Shared state needs to stay in sync across clients.

Avoid if: you’re tied to a legacy relational schema (e.g., Oracle, MSSQL) or need native integrations with existing enterprise systems.

2. Firebase Realtime Database

Type: Pub/Sub System. Broadcasts data changes through channels. When a publisher updates a topic, all subscribed clients get the new data via WebSockets.

Best for: Firebase works best for MVPs, prototypes, or mobile-first apps with lightweight sync needs

Why it stands out:

• WebSocket-powered real-time updates
• Easy setup with built-in auth, hosting, and analytics
• Flexible JSON-based data model

Limitations:

• Deep data nesting leads to messy queries
• No ACID transactions; sync issues in multi-user environments
• Complex security rules and limited control at scale

Avoid if: you’re building production apps with shared state, fine-grained security or compliance needs.

3. Supabase

Type: Postgres + Logical Replication (Pub/Sub hybrid)

Best for: Supabase is best for developers familiar with PostgreSQL who want SQL + subscriptions without building from scratch.

Why it stands out:

• Familiar SQL-based stack with Postgres core
• Logical replication for row-level subscriptions
• Built-in auth, storage, and presence channels

Limitations:

• Updates lag under load due to replication slot pressure
• No built-in frontend reactivity—manual wiring required
• Complex RLS policies can introduce performance bottlenecks

Avoid if: you’re building high-frequency, real-time UIs or collaborative tools. Manual sync layers will slow you down.

4. Realm

Type: Embedded / Mobile-First Database. Runs locally on the device and syncs with the cloud when a connection is available.

Best for: Realm works best for offline-first mobile apps with structured data that syncs when connectivity returns (e.g. field tool or healthcare check-in apps).

Strengths:

• Embedded object store that runs directly on-device
• Background cloud sync when online
• Cross-platform SDKs for mobile and IoT

Limitations:

• No browser-native support or multi-user reactivity
• No subscriptions or dependency tracking
• Built for solo workflows, not shared app state

Avoid if: you need real-time sync across users, especially in browser-based apps.

5. InfluxDB

Type: Time-Series Database. Stores and analyzes streams of time-stamped data like sensor feeds and system metrics.

Best for: Influx works best for time-series and analytics workloads, not app state.

Strengths:

• Ultra-fast ingestion for timestamped data
• Powerful aggregation, downsampling, and alerting
• Optimized for low-memory devices and edge compute

Limitations:

• No ACID transactions or real-time subscriptions
• No WebSocket-based client subscriptions
• Not built for CRUD apps or reactive UIs

Avoid if: you're building a front-end that needs reactive sync or shared application state.

The right real-time database depends on your team, your app, and where you're headed. If you're building with TypeScript and want everything to just work, Convex handles the complexity for you.

Final Thoughts

The right real-time database depends on your team, your app, and where you're headed. If you're building with TypeScript and want everything to just work, Convex handles the complexity for you.

The bottom line: don't overthink it. Pick the platform that matches your current needs and lets you focus on building features users actually want. You can always migrate later if your requirements change. But getting real-time right from the start will give your app the responsiveness users expect.