Architecture Comparison
Firebase
- NoSQL JSON document store
- Google Cloud managed service
- Offline persistence (client-side)
- Security Rules (custom DSL)
- Per-operation billing
- Google ecosystem lock-in
Cosmictron ✓
- SQL relational database
- Self-hosted single binary
- Server-side real-time sync
- Declarative RLS (SQL)
- Fixed infrastructure cost
- No vendor lock-in
The Cost Problem
Firebase's biggest weakness is cost unpredictability. Many developers have experienced bill shock when their app gains traction.
Firebase Blaze
Cosmictron
Real Developer Story
"Our Firebase bill went from $50 to $340 overnight when a blog post hit Hacker News. We weren't even warned—it just charged our card. With Cosmictron, the same traffic spike would have cost... nothing extra." — Indie Developer, Productivity App
Pricing Models
Firebase: Pay-per-operation
- $0.06 per 100K document reads
- $0.18 per 100K writes
- $0.02 per 100K deletes
- Bandwidth: $0.12/GB (egress)
Cosmictron: Fixed infrastructure
- $5-20/month for a VPS (Hetzner, DigitalOcean, etc.)
- Unlimited reads, writes, connections >li>Bandwidth included with VPS
- Scale vertically when needed (your choice)
Data Model: NoSQL vs SQL
Firebase (NoSQL): JSON document tree. Great for simple data, painful for relationships.
Cosmictron (SQL): Relational tables with ACID transactions. Natural for complex data.
Query Comparison: User Feed
Firebase: Denormalize posts into user's feed, update with Cloud Functions. Complex logic spread across multiple services.
Cosmictron: SELECT posts.*, users.name FROM posts JOIN users ON posts.user_id = users.id WHERE posts.user_id IN (SELECT following_id FROM follows WHERE follower_id = ?). Single query, real-time updates via subscription.
When NoSQL Wins
- Simple key-value or document storage
- Massive scale (millions of concurrent users)
- Unstructured/schemaless data
When SQL Wins
- Relational data with foreign keys
- Complex reporting and analytics
- Transactions across multiple entities
- Data integrity requirements
Vendor Lock-in
Firebase: Deep Google Cloud integration. Once you're in:
- Firebase Auth → Google Identity Platform
- Cloud Functions → Google Cloud Functions
- Cloud Storage → Google Cloud Storage
- Exporting data requires Google Cloud SDK
Cosmictron: You own everything:
- Data stored in standard SQLite-compatible format
- Export to PostgreSQL, MySQL, or CSV anytime
- Run on any cloud provider or on-premise
- MIT license—fork and modify as needed
Offline Support
Firebase: Excellent offline support. Data persists locally (IndexedDB) and syncs when online. This is Firebase's killer feature.
Cosmictron: Currently requires connection. Offline support is planned for v2 with CRDT-based conflict resolution. For now, implement optimistic updates with local queuing.
Offline Workaround
For apps requiring offline support today, queue mutations locally and sync on reconnect. This is what Slack, Notion, and Figma do even with their custom backends.
When to Choose Cosmictron
- You need predictable costs (no bill shock)
- You prefer SQL and relational data models
- You want self-hosting for data sovereignty
- You're building B2B/multi-tenant apps
- You need complex real-time queries (joins, aggregations)
- You want to avoid Google ecosystem lock-in
When to Choose Firebase
- Offline-first is a hard requirement
- You're building a simple mobile app
- You want auth with social providers out-of-the-box
- You're already in Google Cloud ecosystem
- You need push notifications without custom backend
Migration from Firebase
Migrating from Firebase to Cosmictron requires some planning:
- Data Export: Use Firebase Admin SDK to export JSON, convert to relational schema
- Security Rules → RLS: Convert Firebase Security Rules to Cosmictron's declarative SQL policies
- Cloud Functions → Reducers: Move business logic from Cloud Functions to reducers (TypeScript or Rust)
- Client SDK: Replace Firebase SDK with Cosmictron client
- Auth: Bring your own auth (JWT) or use external service (Auth0, Clerk)
Typical migration time: 2-4 weeks for a medium-complexity app.