Supabase vs Firebase for beginners

Pick Supabase when the AI builder already speaks it, or when you want Postgres and a free server function. Pick Firebase when you want Google's no-cost quotas and a custom domain without a monthly plan, and you can wait on server functions. Both will leak data if you ship the default open settings. Figures below were read from the pricing pages on 2026-10-22.

The call

Building in Lovable: stay on the built-in backend, or connect your own Supabase project. Lovable's docs say the connector is on every plan, and that the built-in backend uses Supabase's open-source foundation. You do not need a second Firebase project.
Building in Bolt: Bolt Database is on every plan. Supabase is the upgrade when you want the Supabase dashboard, and it requires Pro or Teams.
You want the database, logins, files, and a small API without a monthly bill: Supabase Free includes edge functions (500,000 invocations). Firebase Spark does not include Cloud Functions. That is the practical split for an app that has to hide a secret key.
You want a custom domain on the no-cost plan and a document database: Firebase Hosting includes the domain and SSL on Spark. Supabase's custom domain is a $10/month add-on on Pro, not on Free. The app's own host is a separate decision, covered in where to host.

An anon key, a publishable key, or a Firebase web config is supposed to be in the browser. It is only safe if the rules are on. Read the security checklist before you send anyone the link. Free Supabase projects pause after a week of no use, so a demo you forget about will look broken.

What each free plan includes

Last checked 2026-10-22. Quotas are copied from the provider pricing pages.
	Supabase Free	Firebase Spark (no-cost)
Price	$0	No-cost. No payment method required.
Database	Postgres, 500 MB per project. 2 active projects. Pauses after 1 week of inactivity.	Firestore: 1 GiB stored, 50,000 reads a day, 20,000 writes a day, 20,000 deletes a day, 10 GiB network egress a month.
Auth	50,000 monthly active users. Social OAuth is included. Phone MFA is not on Free.	Auth other than phone is marked no-cost. Phone auth is not on Spark. Identity Platform lists 50,000 monthly active users on Spark.
Files	1 GB storage. Max upload 50 MB. 5 GB cached egress.	Cloud Storage's no-cost bucket quotas are listed on Blaze, not on Spark. Hosting storage is a separate 10 GB.
Server functions	500,000 edge-function invocations included.	Cloud Functions are marked not applicable on Spark. They start on Blaze: 2 million invocations a month at no cost, then $0.40 per million.
Hosting a site	Supabase is the database and API. It is not where you host the website. The API URL is included.	Hosting: 10 GB storage, 360 MB data transfer a day, custom domain and SSL included, multiple sites per project.
Backups	Automatic backups are not included on Free.	The pricing page does not state a backup quota. Do not assume one.
First paid plan	Pro from $25/month, including $10 of compute credit that covers one Micro instance. 8 GB disk, 100,000 monthly active users, then $0.00325 each. Daily backups kept 7 days. Projects on paid plans are not paused.	Blaze is pay as you go. The pricing page does not list a monthly platform fee. Spark quotas remain, then Google Cloud rates. If eligible, Blaze offers $300 in free credit.

Supabase also lists 5 GB of egress, 5 GB of cached egress, and unlimited API requests on Free. Realtime includes 200 concurrent peak connections and 2 million messages. Firebase Realtime Database on Spark allows 100 simultaneous connections, 1 GB stored, and 10 GB downloaded a month. Those are separate products from Firestore. Use Firestore unless a tutorial put you on Realtime Database.

How the AI builders connect

Supabase is the documented path

Lovable can design tables, auth, storage, and edge functions against a Supabase project you own, on every plan. The same docs say most projects never need that, because the built-in backend is already the same kind of stack, billed as Lovable Cloud credits instead of a Supabase subscription. Switching between the built-in backend and your own Supabase project is not automatic, so decide before the tables have real rows. Bolt can use Supabase for the database, auth, and edge functions, and the help center says that connector is Pro and Teams. Bolt Database stays available on Free.

Firebase is code the agent writes

Lovable's and Bolt's integration docs checked for this page describe Supabase, not a Firebase connector. An agent in Cursor or another editor can still install the Firebase client and deploy rules. That works. It also means you have to open the Firebase console yourself and read the rules, because nothing in those builder docs turns Test mode off for you. Firebase's own pricing page lists Gemini in Firebase and a no-cost Firebase Studio allowance. That is Google's builder, not a switch inside Lovable or Bolt.

When to pick each

Pick Supabase if the app already lives in Lovable or Bolt, you want SQL, you want edge functions before you add a card, or you are comfortable with a project that pauses when you ignore it for a week. Budget the jump to $25/month when you need backups or a second active project that must not pause. A custom domain on the Supabase API is extra ($10 per domain per month on Pro) and is not the website domain.
Pick Firebase if you want a document database, the Spark quotas above, and Hosting with your own domain before you pay a monthly plan. Add Blaze when you need a Cloud Function or phone login. There is no published monthly minimum on the pricing page. The risk is Test mode: Firebase's rules docs say that starting mode grants access to all users. Close it before the app is on the internet.
Pick neither yet if you are the only user and the builder already attached a database. A second vendor is another dashboard. Move when a second person needs an account, or when you want a copy of the data that the builder does not control. The host in front of either database is covered separately.

Questions people actually ask

Should a beginner use Supabase or Firebase?

Use Supabase if you are building in Lovable or Bolt, or you want a Postgres database with logins and file storage on a free project. Lovable connects a Supabase project you own on every plan, and its built-in backend uses Supabase's open-source foundation. Bolt's Supabase connector is on Pro and Teams. Use Firebase if you want Google's no-cost Spark plan: Firestore includes 1 GiB, 50,000 reads a day, and 20,000 writes a day, Hosting includes a custom domain, and auth other than phone is no-cost. Cloud Functions are not on Spark, so a server function means adding the Blaze plan. Either way, turn on the access rules before you share the link.

What does Supabase cost after the free plan?

Pro starts at $25/month and includes $10 of compute credit, which covers one Micro database. The pricing page's own example says two Micro projects cost $35/month after that credit. Free is $0, limited to 2 active projects, and free projects pause after 1 week of inactivity. Free includes 500 MB of database, 50,000 monthly active users, 1 GB of file storage, and 500,000 edge-function invocations. Automatic backups start on Pro, kept for 7 days.

Does Firebase have a monthly fee?

The Spark plan is no-cost and does not ask for a card. The Blaze plan is pay as you go. The pricing page does not list a monthly platform fee. Blaze keeps the Spark no-cost quotas, then charges Google Cloud rates. You need Blaze for Cloud Functions and for phone authentication. Hosting on Spark includes 10 GB of storage, 360 MB of data transfer a day, and a custom domain with SSL.

Sources

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