Supabase vs Firebase for a UK SaaS in 2026

Every UK SaaS founder we talk to in 2026 ends up at the same fork in the road:Supabase or Firebase. Both are excellent. Both fail in specific ways for UK businesses. We've shipped ten production platforms on Supabase and three on Firebase — here's the honest comparison nobody publishes because both companies are paying for comparison content.

The headline difference

Supabase is Postgres with a backend bolted on. Firebase is a backend with a NoSQL document store. Almost every other difference flows from this.

If you've ever written SQL — even a little — Supabase will feel like coming home. If you've never written SQL and don't intend to, Firebase's query model is more forgiving (and also more limiting once your data outgrows toy size).

Data residency and GDPR — the bit nobody mentions

UK and EU customers care about where their data lives. This matters more than the marketing pages of either platform admit.

Supabase

Lets you pick the region per project: London (eu-west-2), Dublin (eu-west-1), Frankfurt (eu-central-1). Data physically stays in that region, including backups. Easy to defend in a procurement questionnaire. Easy to write into a Data Processing Agreement.

Firebase

Realtime Database is single-region per project — choose carefully because you cannot migrate later. Cloud Firestore lets you choose a region (multi-region option in europe-west); Cloud Storage similar. Cloud Functions can be pinned to a region. But Firebase Authentication user records are stored multi-regionally by default. That last one is a procurement gotcha — we've seen it kill deals for clients selling to local councils.

Practical takeaway: with Supabase you can write "all customer data resides in the UK" on your security page and mean it. With Firebase, you can get close but you'll need a footnote.

Pricing reality at v1 and v2

Supabase pricing

• Free tier: 2 projects, 500MB database, 1GB file storage, 50,000 monthly active users. Pauses after 7 days inactivity.
• Pro ($25/month per project): 8GB database, 100GB storage, daily backups, no pausing. Most production v1s land here.
• Team ($599/month): SOC 2, point-in-time recovery, log retention. The compliance tier.

Pricing is predictable. We've never had a Supabase bill surprise a client. Database compute is included up to the plan limit — you only pay extra if you go above.

Firebase pricing

• Spark (free): Generous for tiny projects, hard usage limits.
• Blaze (pay-as-you-go): No floor, no ceiling. You pay per read, per write, per function invocation, per GB egress.

Firebase pricing is unpredictable. We've seen a £20/month Firebase project go to £900/month overnight because a developer left a query running in a loop. We've also seen a $3,000 monthly Firebase bill that should have been $30, because nobody noticed Cloud Functions cold-starting on every page load.

Practical takeaway: budget Supabase as a fixed line item, the way you'd budget a phone bill. Budget Firebase as a metered utility that requires monthly attention.

Row-level security: the killer Supabase feature

Supabase uses Postgres row-level security (RLS) — policies written in SQL that the database enforces. The database itself decides who can read what.

The practical effect: your code can't accidentally leak a tenant's data, because the database refuses to return it. Even a buggy API endpoint can't expose customer B's records to customer A. It's the closest thing to a security guarantee you get in modern web development.

Firebase Security Rules are similar in spirit but live in a separate language, applied per collection, and harder to reason about as your schema grows. Many production Firebase apps end up with thin security rules and most authorisation enforced in Cloud Functions — which is fine until somebody finds a missing check.

Practical takeaway: for multi-tenant B2B SaaS, RLS is worth a lot. For a consumer app where every user is independent, the gap matters less.

Auth: Supabase wins for B2B, Firebase wins for consumer

Supabase Auth supports email/password, magic links, OAuth providers, SAML SSO (on Pro), and crucially: it ties auth user IDs to Postgres user rows automatically. Multi-tenant orgs, role-based access, custom claims — all idiomatic.

Firebase Auth has the edge for consumer products: phone-number auth without effort, anonymous auth that promotes cleanly, Apple Sign-In that's pre-wired for App Store submission. If you're building a consumer mobile app that needs phone-number sign-in, Firebase saves you a real chunk of work.

Real-time

Firebase's Realtime Database and Firestore real-time listeners are battle-tested. Supabase Realtime is good and improving but younger.

For a chat app, a multiplayer game, or a live dashboard with thousands of concurrent listeners, Firebase is still our pick. For everything else, Supabase Realtime is plenty.

Mobile SDKs and offline-first

Firebase's iOS, Android and Flutter SDKs are excellent. Offline-first is a first-class concept — the SDK queues writes when offline and reconciles when back online. For a field-service mobile app where workers are in basements and rural areas, this matters.

Supabase's mobile story is improving fast. The Dart and Swift SDKs are good. But true offline-first sync isn't yet at Firebase's level — you'll need to architect the offline-queue yourself, or use something like WatermelonDB on top.

When we pick each one

We pick Supabase for...

• Multi-tenant B2B SaaS with rows owned by orgs (the H2 Intel case)
• Anything with complex queries, joins, aggregations, full-text search
• Products that will eventually need a real admin panel
• UK / EU clients with strict data-residency requirements
• Anything we expect to grow past 10k users (where predictable pricing matters)

We pick Firebase for...

• Consumer mobile apps where offline-first is essential
• Phone-number auth as the primary sign-in
• Real-time multiplayer (chat, presence, live cursors)
• Anything where the Google ecosystem (AdMob, Analytics 360) is a hard requirement
• Hackathon-speed v0 prototypes

The migration trap

Migrating from Firebase to Supabase (or vice versa) is a real piece of work. We've done it twice — both times the client had outgrown their original choice.

Don't let the migration question paralyse you, but do pick deliberately. The decision you make at v0 is rarely the one you'd make at v3, but switching costs are real. If you're at all uncertain and there's any chance of growth, lean Supabase — it gives you more headroom before the migration question gets forced on you.

What about the alternatives?

Brief notes on the other options we get asked about:

• PocketBase: Excellent for solo founders. Single binary, SQLite, ridiculously fast. Production-fine up to a point. Migration to Postgres later is possible but real work.
• Convex: Beautiful developer experience, reactive by default, ideal for real-time. Newer, smaller community, opinionated. We'd consider it for greenfield SaaS where reactive UI is core.
• Appwrite: Open-source self-hosted alternative. Strong if you must self-host. The platform is competent; the ecosystem is thinner than Supabase or Firebase.
• NeonDB + Auth.js + custom backend: The à la carte approach. Most flexibility, most work. Right for teams with senior backend engineers, wrong for solo founders.