- Postgres versus documents
- Side by side
- The free tier rules that catch people out
- Lock-in and leaving later
- How to decide in an afternoon
- For non-technical founders
- Auth, storage and functions
- Backups and recovery
- Signs you picked the wrong one
- Why switching later takes longer
- My verdict
- Frequently asked questions
Supabase suits apps whose data has clear relationships, because every project is a full Postgres database you can query with SQL. Firebase suits apps that want Google's document database, mature mobile tooling and deep links with Google Cloud. Pick based on how your data is shaped and how much you want to avoid lock-in.
Both give you a database, user login, file storage and server functions without running your own servers. The choice you're really making is about your data model and how easily you could leave later.
Postgres versus documents
Supabase's own docs say every project gets a full Postgres database, not a Postgres abstraction, and that its auth, storage, real-time and functions are built on that database. Firebase's best-known database, Cloud Firestore, stores data as documents in collections. Relational data, such as customers, orders and invoices, fits naturally in Postgres. Flexible, nested app data fits documents well.
Side by side
| Area | Supabase | Firebase |
|---|---|---|
| Database | Full Postgres database | Cloud Firestore document database |
| Querying | SQL and generated APIs | Firestore queries and SDKs |
| Open source | Open-source platform, can be self-hosted | Google-hosted service |
| Free tier rule | Free projects pause after low activity over 7 days | Free quota applied daily, resets around midnight Pacific time |
| Best fit | Relational data and SQL fans | Mobile apps and Google Cloud users |
The free tier rules that catch people out
Here's what to know before you build a side project on either. Supabase's docs say it pauses Free Plan projects that show low activity over a 7-day period, and its billing docs explain the free project limit, which works out at two free projects in total. Firebase's docs say the Cloud Firestore free quota is applied daily and resets around midnight Pacific time, and that you need billing enabled on your Google Cloud project for more. So a quiet Supabase demo can go to sleep, and a busy Firebase day can hit a daily limit. Set alerts on both.
Lock-in and leaving later
- A Postgres database can be exported with standard tools and moved to any Postgres host.
- Document data can be exported too, but moving it into a relational database means reshaping it.
- User accounts are the hardest part to move on any platform, so check how password hashes and social logins transfer.
How to decide in an afternoon
- Sketch your main data: what are the things, and how do they relate?
- Build one small feature, such as sign-up plus one list, on both.
- Check how real-time updates behave with two users editing at once.
- Export your data from both and see what you get.
- Pick the one your team understood fastest.
If you're still choosing your front end, my explainer on single-page versus multi-page applications covers that decision, and my story of building a lead calculator in a weekend shows how far a small build can go.
For non-technical founders
If you're hiring a developer, ask which one they know best and why. A developer who's fluent in one platform will usually ship faster on it, and that matters more early on than small differences between the two. Ask them to document the data model and set up exports from day one.
Auth, storage and functions
Both platforms bundle user login, file storage and server functions with the database. On the Postgres side, Supabase's docs describe auth, storage, real-time and edge functions as built on top of the database, so permissions can be written as database rules. On the document side, security rules control who can read and write each document. Either approach works, but they feel different to write, so try a small permissions rule on both.
Look closely at how each handles social logins, magic links and multi-factor authentication if your users expect them.
Backups and recovery
Supabase's database docs say it manages daily database backups and offers point-in-time recovery on higher plans. Whatever you choose, check how backups work on the plan you're on, how far back you can restore, and whether you can trigger a restore yourself. Then test a restore before launch, because an untested backup is only a hope.
Signs you picked the wrong one
- You keep copying the same data into several documents to make queries work.
- Simple reports need lots of code because the database can't join data.
- Your free project keeps pausing or hitting daily limits during demos.
If you see these early, switching is still quick. Later, it's a project.
Why switching later takes longer
The longer you build on one platform, the more of your app depends on its specific features. A move later means rewriting queries, security rules and sometimes your data model. That's not a reason to freeze, but it's a good reason to spend an extra day choosing well at the start, while switching is still quick.
My verdict
If your data looks like a spreadsheet with linked tabs, I'd lean towards the Postgres option. If you're building a mobile-first app on Google Cloud with flexible data, the document database is a natural fit. Whichever you choose, read the free tier rules, set alerts and keep exports running.
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Frequently asked questions
What's the main difference between Supabase and Firebase?
Supabase gives every project a full Postgres database, while Firebase's Cloud Firestore is a document database.
Does Supabase pause free projects?
Its docs say Free Plan projects with low activity over a 7-day period are paused, and can be restored.
How does Firebase's free quota work?
Firebase's docs say the Cloud Firestore free quota is applied daily and resets around midnight Pacific time.
Is Supabase open source?
Yes, and it can be self-hosted, which helps if you want to avoid lock-in.
Which is easier to leave later?
A Postgres database moves easily to other Postgres hosts. Document data needs reshaping for a relational database.
Which is better for mobile apps?
Both support mobile apps. Firebase has long-standing mobile tooling, while Supabase offers client libraries for common frameworks.
How do backups work on Supabase?
Its docs say it manages daily database backups and offers point-in-time recovery on higher plans.
How do I keep my free Supabase project from pausing?
Its docs explain that Free Plan projects pause after low activity over 7 days, so keep the project active or restore it when needed.
Can I use Supabase and Firebase together?
Some teams do, for example using one for the database and the other for notifications. It adds complexity, so only do it for a clear reason.
