Firebase vs Supabase: A Security Comparison

You picked a backend — or your AI builder picked one for you — and now you want to know whether you chose the safe one. Firebase or Supabase: which is more secure? It's a fair question, and you'll find plenty of strong opinions online. Most of them are missing the point.

Here's the honest answer up front: neither is inherently more secure than the other. They share the same core design, so they share the same core risk. What determines whether your app leaks isn't which logo is on your dashboard — it's whether you configured the rules layer correctly, and an AI builder gets that layer wrong on both platforms in nearly identical ways.

So this is an even-handed comparison, not a fan post: how each one protects you, how each one leaks when an AI builds it, and what to check — so you can secure whichever you're already on.

⚡ TL;DR

• Both ship a public client key (Supabase anon key, Firebase web config). Neither is a leak — they're public by design. Don't panic about either.
• Real protection is the rules layer: Supabase RLS (SQL policies on Postgres) vs Firebase Security Rules (a rules language over Firestore/Storage). Same job, different syntax.
• The classic AI failure is the same on both: a rule that allows everyone — USING (true) on Supabase, allow read, write: if true; on Firebase. That's the real risk, not the public key.

The thing both platforms have in common (and why it matters)

Start here, because it's the foundation everything rests on. Firebase and Supabase are both backend-as-a-service platforms that let your frontend talk almost directly to the database. There's usually no server of yours in the middle checking "is this person allowed to do this?" — so the permission checks can't happen there. They have to happen somewhere the platform enforces on its own servers, on every request. That "somewhere" is the rules layer:

• On Supabase, it's Row Level Security (RLS) — security policies written in SQL that the database checks on every query.
• On Firebase, it's Security Rules — a rules language the platform evaluates on every read and write to Firestore or Storage.

Different names, different syntax, identical purpose: a rule the backend enforces so your app can't forget it. Get the rules right and your app is safe even though the client key is public; get them wrong and your data is open to anyone, even though nothing was "hacked." That's equally true on both. (Supabase is the default backend for most AI builders; Firebase shows up less often but features in some of the largest breaches.)

The public key, on both sides: don't cry wolf

Before we compare protections, let's defuse the same false alarm on both platforms, because it sends founders chasing the wrong fix on either one.

Both Firebase and Supabase ship a public client key that's meant to live in your frontend. Supabase gives you an anon key; Firebase gives you a web config (including the apiKey). Both belong in the browser, and neither is a secret. They're identifiers that route requests to your project, not credentials that grant access — so neither is a leak when it shows up in your frontend code or a network request. If a scanner flags either one as a critical exposure and tells you to rotate it, that scanner is crying wolf.

🐺 Not a real problem

Seeing your Supabase anon key or your Firebase web config in your frontend is expected. Both are public by design. Rotating them gains you nothing. The real question on both platforms is always: do my rules — RLS or Security Rules — actually restrict who can read and write?

And both platforms have a real secret that's easy to confuse with the harmless public one: Supabase's service_role key and Firebase's service-account key each bypass the rules layer entirely and must stay server-side. These are the credentials that actually end your week if they leak. The trap on both platforms is identical: don't waste energy hiding the public key, and never ship the secret one in client code or a public repo.

How each one protects you: RLS vs Security Rules

Now the real comparison. Both are rule systems, but they look and feel different.

Supabase RLS — SQL policies on Postgres. Supabase is a real PostgreSQL database, so its rules are written in SQL. You attach policies to each table defining who can do what; a safe policy reads auth.uid() = user_id, so a row is only visible or editable if the logged-in user's ID matches the user_id column. The catch: RLS is off by default on new tables, and a table with RLS disabled (or no policy) is fully exposed through the public anon key.

Firebase Security Rules — a rules language over Firestore/Storage. Firebase is a document store, and its rules use a dedicated rules language. You write match blocks for paths, each with allow conditions; a safe rule checks request.auth.uid == userId. Firebase splits rules across two separate rulebooks — database and Storage — a frequent source of mistakes, because people secure one and forget the other.

The mental model transfers: in both, you're writing a per-request check that says "only the owner of this data may touch it" — Supabase as a SQL condition on a row, Firebase as a path match with an auth check. Learn the concept once and you can read either.

How each one leaks when an AI builds it

This is where it gets practical, because the failure modes rhyme almost word for word.

The "allow everyone" rule. The number-one mistake on both platforms, which an AI tool produces constantly because open rules make the app "work" in the preview:

-- Supabase: a policy that lets anyone read every row
create policy "public read" on profiles
  for select using ( true );

// Firebase: a rule that lets anyone read and write everything
match /{document=**} {
  allow read, write: if true;
}

using (true) and if true are the same idea: "yes to everyone, always." Both leave your data open to anyone holding the public key — which is everyone. This pattern is documented in the wild: CVE-2025-48757, disclosed in May 2025, found that 170 of 1,645 scanned Lovable/Supabase apps (about 10.3%) were leaking through the public anon key against tables with missing or USING (true) RLS. It was the first published CVE for the category, and the pattern recurs across Bolt, v0, Cursor, and Replit.

The "looks locked but isn't" rule. Both platforms have a trap where a rule seems to add security but doesn't. On Supabase, a USING (true) policy passes a naive scan because a policy technically exists — yet it permits everyone. On Firebase, allow read, write: if request.auth != null requires a login but lets any logged-in user reach everyone else's data, because it's missing the ownership check. Same shape: present but toothless.

Storage. Both store files separately from the database, and both leak there. On Supabase, the classic mistake is a bucket left public by default with no access policy. On Firebase, it's an open Storage bucket under permissive rules — the cause of the Tea app breach in July 2025, which exposed roughly 72,000 images including about 13,000 selfies and government IDs (a second breach exposed more than 1.1 million private direct messages). Files are the crown jewels on either platform, and the storage rule is what protects them.

How to check your own app

Whichever platform you're on, the checks map onto each other. None of this requires writing code.

If you're on Supabase: open the dashboard → Table Editor and, for every table holding user data, confirm RLS is enabled with a policy that checks ownership (auth.uid() = user_id), not using (true). Check Storage to confirm sensitive buckets aren't public. And confirm the service_role key is nowhere in your frontend or repo.

If you're on Firebase: open the Console → Firestore (or Realtime Database) → Rules and confirm you don't see allow read, write: if true; or a test mode banner. Open Storage → Rules separately — the step people skip — and confirm the file bucket is owner-scoped. Then search your project and repo for "type": "service_account" and private_key; if that file is reachable by users, treat it as a leak.

On either platform, the final test is the same: open your app's network traffic in the browser's dev tools. If you can read other people's data or files using only the public key, so can anyone else.

So which one should you use?

We're not handing you a winner, because the honest answer is that the secure choice is the one you configure correctly. Both can be locked down tight; both can leak everything. The deciding factor is your rules layer, not the brand. If it helps you reason about a choice:

• Supabase is a SQL/Postgres world. If you or your AI think in SQL, RLS feels natural — once you remember to enable it on every table. It's the default for most AI builders, so there's more vibe-coding guidance and more documented incidents.
• Firebase is a document/NoSQL world with a dedicated rules language and tight integration with Google's auth and hosting. Its main gotcha is the two separate rulebooks (database and Storage).

If you've already built on one, don't switch for security reasons — that's a large, risky project that won't make you safer, since a misconfigured Supabase is exactly as exposed as a misconfigured Firebase. Spend that energy auditing your rules instead. To go deep on whichever you're on, start with the cornerstones: Supabase security for AI-built apps and Firebase security for AI-built apps, and if you're on Firebase, the common rule mistakes are in Firebase Security Rules: 12 mistakes AI tools make.

FAQ

Is Firebase or Supabase more secure?

Neither is inherently more secure. Both let the frontend talk almost directly to the database, so both depend entirely on a rules layer — Supabase RLS or Firebase Security Rules — that you must configure correctly. A properly locked-down version of either is safe; a misconfigured version of either leaks. The platform brand isn't the deciding factor; your rules are.

Do both Firebase and Supabase expose a public key?

Yes, and that's by design. Supabase ships a public anon key and Firebase ships a public web config (including the apiKey); both are meant to live in your frontend. Seeing either in your code is not a leak. The credentials you must keep secret are Supabase's service_role key and Firebase's service-account key, both of which bypass the rules layer entirely.

Is RLS the same as Firebase Security Rules?

They serve the same purpose — a per-request permission check the backend enforces so your app can't bypass it — but they're built differently. RLS is SQL policies on a Postgres database (for example auth.uid() = user_id). Firebase Security Rules use a dedicated rules language over Firestore and Storage (for example request.auth.uid == userId). Learn the ownership-check concept once and you can read both.

The bottom line

Firebase versus Supabase isn't a security contest, because they're the same bet in two dialects: a public client key, a rules layer that does the real protecting, and a secret server key you must never ship. The AI that built your app makes the same mistake on both — a rule that allows everyone — and that, not the public key, is what leaks. An attacker can probe either backend in minutes with nothing but the public key; find your open rule or open bucket first, and keep checking, because every deploy your AI ships brings new tables, new buckets, and new gaps.