Firebase Alternatives for SaaS in 2026: Supabase, AWS Amplify, and Custom

We migrated 3 SaaS apps off Firebase. Here is when to stay, when to leave, and what to switch to.

By David Friedman, Founder of AppBrewers

Firebase has become the default backend for countless MVPs, and for good reason. It offers a comprehensive suite of services that allow developers to build applications quickly without worrying about infrastructure management. However, as applications scale, Firebase's limitations become apparent and costs can rise unexpectedly.

In 2025, we migrated three SaaS applications off Firebase, each taking a different path: two to Supabase and one to a custom backend solution. This article shares our experience to help you make an informed decision about when to stay with Firebase and when to explore alternatives.

When Firebase Is Perfect

Firebase excels in specific scenarios, particularly for applications at certain stages of development and user base size.

Stage-Based Analysis

Stage	Users	Firebase Cost	Why It Works
MVP	0-1,000	0-50 Euro/month	Free tier covers everything
Growth	1,000-10,000	50-300 Euro/month	Still cheap, still scalable
Scale	10,000-50,000	300-1,500 Euro/month	Costs rise but manageable
Enterprise	50,000+	1,500-5,000 Euro/month	Time to evaluate alternatives

For startups in the MVP and early growth stages, Firebase provides an excellent balance of functionality and cost. The free tier is generous enough to validate product-market fit without significant financial commitment. The managed infrastructure eliminates operational overhead, allowing small teams to focus on product development rather than backend concerns.

At the growth stage (1,000-10,000 users), Firebase remains cost-effective while offering the scalability needed to support expanding user bases. The platform's auto-scaling capabilities handle increased load without manual intervention.

The scale stage (10,000-50,000 users) is where the trade-offs become more apparent. While Firebase can technically support this many users, costs begin to rise noticeably, and certain limitations may impact development velocity.

For applications with 50,000+ users, it's time to seriously evaluate alternatives. At this point, the combination of increasing costs and potential limitations often makes migration worthwhile.

Firebase Limitations at Scale

As applications grow beyond the initial stages, several Firebase limitations become increasingly problematic:

Firestore Query Limitations

Impact: Complex joins are difficult to implement efficiently.

Technical Details: Firestore is a NoSQL document database that doesn't support traditional SQL joins. While it allows limited querying capabilities through its query API, complex relationships require denormalization or multiple queries.

Workaround: The most common approach is data denormalization, where redundant data is stored in multiple documents to avoid joins. This leads to increased storage costs and the risk of data inconsistency when updates aren't propagated across all copies.

Example: In a social media application, instead of storing posts in one collection and user information in another, you might duplicate user data in each post document. This simplifies retrieval but creates maintenance challenges when user profiles change.

Cloud Functions Cold Starts

Impact: 2-5 second latency on function execution.

Technical Details: Cloud Functions for Firebase use a serverless architecture that scales to zero when not in use. While cost-effective, this results in "cold starts" when functions are invoked after being idle, where the runtime environment must be initialized before the function code executes.

Workaround: The recommended approach is to keep functions warm by periodically triggering them. This can be done with scheduled HTTP requests or other mechanisms, but it adds operational complexity and increases costs.

Example: An e-commerce application processing payments might experience noticeable delays during checkout if the payment processing function hasn't been recently invoked, impacting user experience.

Vendor Lock-in

Impact: Hard to migrate away from Firebase services.

Technical Details: Firebase provides tightly integrated services (authentication, database, storage, etc.) that work well together but create dependencies on Google's ecosystem. Migrating away requires rebuilding multiple components.

Workaround: The best strategy is to abstract data access layers early, even in small applications. This creates an abstraction that can be swapped out later, though it adds initial development overhead.

Example: Implementing a repository pattern that can be configured to use different database backends allows for smoother migration when the time comes.

Real-time Costs

Impact: 100K+ concurrent connections become expensive.

Technical Details: Firebase's real-time database and Firestore real-time listeners use persistent connections that consume resources. As the number of concurrent connections grows, costs increase significantly.

Workaround: For applications that don't require real-time updates for all operations, polling can be a more cost-effective approach, though it introduces latency and complexity.

Example: A dashboard application might use polling for data updates that don't require immediate feedback, while keeping real-time updates for critical notifications.

No SQL Support

Impact: Analytics queries become slow and complex.

Technical Details: While Firestore supports some SQL-like queries, it lacks the full power of SQL for complex analytics and reporting. Aggregations across large datasets are particularly challenging.

Workaround: Exporting data to a dedicated analytics platform like Google BigQuery allows for more sophisticated analysis but adds operational complexity.

Example: Generating monthly reports on user behavior might require complex queries that are inefficient or impossible to perform directly in Firestore, necessitating data export to another system.

The Alternatives

When Firebase limitations or costs become problematic, several alternatives offer different trade-offs. The right choice depends on your specific requirements, team expertise, and long-term vision.

Supabase

Supabase has emerged as a popular Firebase alternative, offering a PostgreSQL-based backend with real-time capabilities.

Key Factors:

Factor	Supabase	Firebase
Database	PostgreSQL	Firestore (NoSQL)
Real-time	Yes	Yes
Auth	Yes	Yes
Storage	Yes	Yes
Edge functions	Yes	Cloud Functions
Self-hosting	Yes	No
SQL queries	Yes	No
Pricing	Cheaper at scale	Cheaper at start

Technical Architecture: Supabase provides a PostgreSQL database with real-time capabilities through webhooks and a WebSocket-based real-time API. It includes authentication, storage, and edge functions similar to Firebase, but built on open-source components.

Best for: Teams that need SQL capabilities, complex queries, or the option to self-host their infrastructure.

Migration Considerations: Moving from Firebase to Supabase requires significant changes to data modeling, as you're shifting from a NoSQL to a relational database. The migration process typically involves:

1. Designing a relational schema that represents your data
2. Writing migration scripts to transform existing data
3. Updating client-side code to use the new API patterns
4. Implementing authentication and real-time features using Supabase's SDKs

Example: A SaaS application with complex user permissions might benefit from Supabase's SQL capabilities to implement fine-grained access control that would be difficult to achieve in Firestore's document-based model.

AWS Amplify

AWS Amplify provides a comprehensive set of tools and services for building scalable web and mobile applications on AWS infrastructure.

Key Factors:

Factor	Amplify	Firebase
Ecosystem	AWS services	Google services
Flexibility	High	Medium
Complexity	High	Low
Enterprise features	Extensive	Limited
Team size needed	2+ backend devs	0-1 backend devs

Technical Architecture: Amplify integrates with AWS services like DynamoDB, Cognito, Lambda, and API Gateway to provide a managed backend experience. It offers both a CLI for infrastructure-as-code and a library for client-side integration.

Best for: Enterprise applications, teams with AWS expertise, or applications that need deep integration with other AWS services.

Migration Considerations: Migrating to AWS Amplify requires familiarity with AWS services and concepts. The migration process typically involves:

1. Setting up AWS resources using Amplify CLI
2. Implementing backend logic with AWS Lambda
3. Configuring authentication with Amazon Cognito
4. Setting up API Gateway endpoints
5. Updating client applications to use the Amplify libraries

Example: A data-intensive application that already uses other AWS services like S3 or Redshift would benefit from Amplify's tight integration with the AWS ecosystem.

Custom Backend (Node.js + PostgreSQL)

For applications with specific requirements or at very large scale, a custom backend provides maximum control and flexibility.

Key Factors:

Factor	Custom	Firebase
Control	Total	Limited
Cost at scale	Lower	Higher
Development time	2-3x longer	Fast
Maintenance	Requires dedicated backend dev	Minimal
Flexibility	Unlimited	Platform-defined

Technical Architecture: A custom backend typically involves:

• A database (PostgreSQL, MongoDB, etc.)
• An API layer (Node.js, Express, FastAPI, etc.)
• Authentication system (Auth0, custom JWT, etc.)
• Background workers for processing tasks
• Infrastructure deployment (Docker, Kubernetes, etc.)

Best for: Applications with 100K+ users, complex business logic, or specific regulatory requirements.

Migration Considerations: Building a custom backend requires significant development resources and expertise. The migration process typically involves:

1. Designing and implementing the database schema
2. Building API endpoints with appropriate business logic
3. Implementing authentication and authorization
4. Setting up infrastructure and deployment pipelines
5. Migrating existing data
6. Updating client applications to use the new API

Example: A financial application with complex compliance requirements might benefit from a custom backend that can be precisely tailored to regulatory standards.

Our Migration Decision Tree

To help determine the right path for your application, we've developed a decision tree based on our migration experience:

1. Are you building an MVP?

   • Yes → Use Firebase (fastest path to market)
   • No → Continue to next question

2. Are you over 50K users?

   • Yes → Consider custom backend (maximum control at scale)
   • No → Continue to next question

3. Do you need complex SQL queries?

   • Yes → Supabase (SQL capabilities with Firebase-like experience)
   • No → Stay on Firebase (if costs are acceptable)

This decision tree provides a starting point, but the right choice depends on additional factors like team expertise, regulatory requirements, and long-term product vision.

Migration Costs and Considerations

Migrating from Firebase to another platform involves significant effort and cost. Here's what to expect based on our experience:

Firebase to Supabase

• Timeline: 2-4 weeks
• Cost: 3,000-8,000 Euro
• Risk: Low (similar developer experience)

The primary challenge is transitioning from NoSQL to relational data modeling. Supabase's PostgreSQL database requires careful schema design, and existing data needs to be transformed into the new structure.

Firebase to AWS Amplify

• Timeline: 4-8 weeks
• Cost: 8,000-15,000 Euro
• Risk: Medium (requires AWS expertise)

The migration involves learning AWS services and re-implementing functionality using AWS-specific components. The complexity increases with the number of Firebase features being replaced.

Firebase to Custom Backend

• Timeline: 8-16 weeks
• Cost: 15,000-40,000 Euro
• Risk: High (significant development effort)

Building a custom backend requires the most resources but offers the most control. The timeline can vary significantly based on the complexity of the application and the specific requirements.

Making the Right Choice

The decision to migrate from Firebase should be based on a careful evaluation of your specific needs, team capabilities, and long-term vision. Here are key considerations:

Evaluate Your Technical Requirements

• Do you need complex queries that are difficult in Firestore?
• Are you experiencing performance issues with real-time features?
• Do you have specific compliance or regulatory requirements?
• Do you need more control over infrastructure and deployment?

Consider Team Expertise

• Does your team have experience with the target platform?
• Can you acquire the necessary skills, or would you need to hire?
• How much time can you dedicate to learning and migration?

Assess Long-term Vision

• Where do you see your application in 2-5 years?
• Will the chosen platform support your growth plans?
• Are there other services you'll need to integrate?

Test with a Pilot Project

Before committing to a full migration, consider migrating a smaller subset of functionality to the new platform. This allows you to evaluate the technology, identify challenges, and build expertise with lower risk.

Need Help Choosing?

We have built on Firebase, Supabase, and custom backends. We will tell you which fits your stage and budget.

appbrewers.com/get-a-quote [email protected]

Originally published on the AppBrewers Blog.