Best Mobile App Backend for AI-Built Apps

The short answer

For most AI-assisted mobile apps:

• Choose Supabase for relational data, SQL, row-level security and easier data export.
• Choose Firebase for offline-first Firestore clients, native SDKs and the smoothest FCM path.
• Choose Convex for TypeScript apps built around reactive queries.
• Choose Appwrite when self-hosting and bundled messaging are requirements.
• Choose PocketBase for prototypes, internal tools and controlled single-server deployments.
• Build a custom Postgres API when portability and complex business logic justify more infrastructure.

The hardest requirement should decide the platform. SDK calls are replaceable; database models, authorization policies and offline architectures are not.

Best mobile app backend comparison

Backend	Best for	Main limitation	Portability
Supabase	SQL, joins, RLS and relational products	No native mobile offline-sync engine	High for data; medium for platform APIs
Firebase	Offline Firestore, native SDKs and FCM	Document modeling and platform-specific rules	Low to medium
Appwrite	Integrated cloud or self-hosted infrastructure	Offline sync must be assembled	Medium
Convex	Reactive TypeScript applications	Authorization must be enforced in every public function	Low to medium
PocketBase	Prototypes and small single-server products	Pre-1.0 compatibility warning	Medium
Managed Postgres/API	Maximum control and vendor independence	You operate the API and supporting services	Highest

Supabase provides PostgreSQL with extensions including pgvector and PostGIS. RLS must be enabled on every table in an exposed schema (Supabase database overview, RLS guide).

Firestore automatically synchronizes active listeners and supports offline reads, queries and writes on Android and Apple platforms. Conflicting offline changes to the same document use last-write-wins, so collaborative editing and inventory systems may still need domain-specific conflict handling (Firestore offline documentation).

Supabase vs Firebase vs Appwrite and the other options

Supabase: the relational default

Supabase is the practical default for products with organizations, memberships, subscriptions, permissions or reporting.

• Good fit: SaaS, marketplaces, booking systems and products combining embeddings with relational data.
• Watch: AI-generated RLS is often incomplete. Test anonymous, owner, member and administrator access separately.
• Offline: add a local database and explicit synchronization strategy.
• Push: call Expo Push, FCM or APNs from an Edge Function; Supabase does not operate a native device push network (push guide).

The local CLI runs the database, Auth, Storage and Edge Functions together. SQL migrations provide a reviewable deployment trail (local development guide).

Firebase: the offline-first choice

Firebase is the safer shortcut when intermittent connectivity is a core requirement. Firestore persistence defaults on Android and Apple clients, and Firebase provides official SDKs, Security Rules, emulators and FCM.

• Good fit: chat, field-recording, consumer and FlutterFlow apps.
• Watch: document reads, listener reconnects and index reads affect billing.
• Migrations: version document shapes and use idempotent backfills; Firestore has no relational migration system.
• Portability: denormalized documents, Security Rules and Cloud Functions triggers take work to replace.

Firestore offers regional and multi-region locations. Multi-region configurations replicate across regions; regional deployments can reduce cost and write latency (location documentation).

Appwrite, Convex and PocketBase

Appwrite bundles Auth, databases, storage, functions, realtime and messaging. It runs on Appwrite Cloud or self-hosted Docker (Appwrite overview, self-hosting guide). Push delivery still requires separately configured APNs or FCM providers (push documentation).

Convex reruns subscribed TypeScript queries when their dependencies change (realtime documentation). It has no RLS: every public query or mutation must check authorization in backend code (authentication and authorization).

PocketBase packages SQLite, auth, files, realtime and a dashboard into one executable. It creates commit-ready JavaScript migrations, but the project warns that backward compatibility is not guaranteed before 1.0 and does not recommend production-important use (PocketBase documentation). Editorial recommendation: reserve it for pilots, internal tools and small products with reliable backups.

Offline support and push notifications

Realtime is not offline-first. Offline-first software stores useful data locally, queues writes, reconnects safely and resolves conflicts.

Platform	Offline behavior	Push path
Supabase	Build a local cache, queue and sync process	Backend calls Expo, FCM or APNs
Firebase	Firestore caches data and synchronizes writes	FCM through a trusted server or Cloud Function
Appwrite	Add a local store and push-pull replication	Messaging routes through APNs or FCM
Convex	Reactive online client; persistent offline writes need extra design	Action or server calls a push provider
PocketBase	Application-owned offline logic	Hook or worker calls a push provider
Custom API	Application-defined	Worker calls a push provider

Appwrite’s offline guide requires a local store such as SQLite or RxDB, connectivity detection, replication and conflict resolution (Appwrite offline guide). Apply the same assumption to Supabase, Convex and PocketBase unless you add a synchronization product.

FCM requires a trusted sending environment; never put privileged credentials in the app (FCM architecture). Expo recommends sending from the backend, processing receipts and removing unregistered tokens. Its service is free and currently limits projects to 600 notifications per second (Expo push guidance).

Pricing cliffs to model before launch

These are verified pricing facts from official pages. Confirm current prices and quotas before committing.

Backend	Entry point	Costs to model
Supabase	Free: 500 MB database, 1 GB files, 50,000 MAU; Pro: $25/month	Compute, database size, egress, realtime and projects
Firebase	Spark is no-cost; Blaze is pay-as-you-go	Reads, writes, index reads, storage, egress and functions
Appwrite Cloud	Free: 500,000 reads and 250,000 writes monthly	Operations, storage, bandwidth and messaging providers
Convex	Free/Starter; Professional: $25 per developer/month	Calls, I/O, compute, files and egress
PocketBase	Free software	Hosting, backups, monitoring and operator time
Managed Postgres/API	Provider-specific	Database, API, auth, files, logs, egress and support

Supabase Pro currently includes 8 GB of database disk, 100 GB of file storage, 250 GB of egress and 100,000 MAU before overages (Supabase pricing). Firestore’s free quota includes 50,000 document reads and 20,000 writes per day, with only one database per project receiving the quota (Firestore billing). Convex publishes separate rates for calls, compute, storage, I/O and networking (Convex pricing).

Illustrative calculation: 2,000 daily users opening a feed twice and reading 30 documents each time produce about 120,000 reads per day, before rule-dependent reads, refreshes or realtime updates. This is a workload model, not a Firebase quote.

A custom stack is not automatically cheaper. Neon describes a typical Launch-plan spend of $15/month for intermittent load and 1 GB, but that excludes your API, files, push, logging and engineering time (Neon pricing).

Security rules for an AI-built backend

Never ship service-role keys, database passwords, Firebase service-account credentials, Appwrite API keys or push-provider credentials in a mobile binary.

Check	Required proof
Authorization	Every read and write is constrained by user, tenant and role
Privileged operations	Billing, role changes, AI calls and push sends run server-side
Rules	Deny cases are tested in CI
Schema	Constraints, indexes and migrations are version-controlled
Files	Private files use checked or expiring URLs
Abuse	Expensive actions have rate limits, quotas and idempotency keys
Recovery	Backups have been restored successfully

Supabase service roles bypass RLS, Firebase Admin SDKs bypass client Security Rules, PocketBase superusers bypass API rules, and Appwrite server keys can have broad scopes. Keep these capabilities narrow.

Convex has no RLS safety net, so every public function must validate arguments, identity and resource ownership. PostgreSQL RLS can add defense in depth and defaults to deny when enabled without a matching policy (PostgreSQL RLS documentation).

Best backend by mobile builder

1. FlutterFlow: choose Firebase when offline Firestore or automated push is central. FlutterFlow’s push setup uses FCM and requires Firebase Blaze because it uses Cloud Functions (FlutterFlow push documentation). Choose Supabase for SQL and relational reporting; FlutterFlow supports both authentication systems (auth integrations).

2. Expo or React Native: choose Supabase for conventional SaaS data or Convex for TypeScript-heavy realtime products (React Native documentation). Choose Firebase when offline writes are a primary requirement.

3. Lovable-to-mobile wrapper: keep the React app connected to Supabase or Lovable Cloud and package it with Capacitor (Capacitor documentation). Test keyboards, deep links, OAuth redirects, uploads, backgrounding and offline failures on physical devices. Confirm who owns the backend data and credentials (Supabase’s Lovable backend guide).

4. Custom Swift, Kotlin or Flutter: Firebase offers the broadest integrated mobile path. Choose Supabase for relational data or a custom Postgres API when authorization, audits and domain workflows require tighter control.

Production-readiness checklist

Before committing, build one vertical slice covering sign-in, tenant-owned data, file upload, a privileged action, a realtime update and a denied cross-user request.

• Test reads, writes and conflicts in airplane mode.
• Prove tenant isolation with automated deny tests.
• Deploy schemas and policies from version control.
• Map user actions to billable operations.
• Restore a backup.
• Export data and document replacement boundaries.

Bottom line

Choose Supabase for most relational AI-assisted products, Firebase when offline synchronization and integrated mobile services decide the architecture, Convex for reactive TypeScript apps, Appwrite for bundled self-hostable infrastructure, and PocketBase for small deployments that accept its pre-1.0 limits.

Choose a custom Postgres API only when control, specialized workflows or portability justify operating more components. Whatever you select, keep privileged credentials server-side, test deny rules, commit migrations and model costs before launch.