Supabase is the best default for a first AI-built app: Postgres, sign-in, file storage and 50,000 monthly users on the free plan. Choose Neon for plain Postgres, Firebase for Flutter or Android, Convex for live data, Turso or Cloudflare D1 for small SQLite apps and Appwrite as an open-source alternative. Read each pause and expiry rule before real users arrive.
AI app builders write the screens quickly. What decides whether the app survives is the backend: where the data lives, who is allowed to read it and what happens when the free plan runs out. These are the free options worth using, each with the catch that surprises beginners.
The 10 picks
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Free plan, 2 projectsSupabase
Postgres database, sign-in, file storage and serverless functions in one dashboard. Free: 500 MB of data, 1 GB of files, 50,000 monthly users and 2 projects. A free project pauses after a week of low activity and has no automatic backups.
Spark plan, no cardFirebase
Google's sign-in, Firestore database and hosting. The Spark plan needs no card: 50,000 monthly sign-in users and 1 GiB of Firestore. Cloud Storage and Cloud Functions need the pay-as-you-go Blaze plan, which needs a card.
Free plan, no cardNeon
Serverless Postgres with branches for testing changes. Free and no card: 100 projects, 1 GB each, 100 compute-hours a month. Compute sleeps after 5 idle minutes, so the first query afterwards is slower.
Free plan, no cardTurso
Hosted SQLite built for many small databases. Free and no card: 100 databases, 5 GB and 500 million rows read a month. It is SQLite, so SQL an AI wrote for Postgres usually needs changes.
Free planConvex
A TypeScript backend where queries update live on every screen. Free plan: 1 million function calls and 0.5 GB of data a month. It has its own data model rather than SQL, which suits real-time apps.
Free plan, 2 projectsAppwrite Cloud
Open-source alternative to Supabase with auth, database, storage and functions. Free: 2 projects and 75,000 monthly users. Projects pause after a week of inactivity, and the Student Pack adds six months of the Education plan.
Free daily limitsCloudflare D1 and KV
SQLite and key-value storage that plug straight into Cloudflare Workers. D1 free: 5 million rows read and 100,000 written a day. Since 1 September 2026 queries fail once a daily cap is hit and resume at midnight UTC.
Free plan, 1 databaseUpstash Redis
Serverless Redis for rate limiting and caching, billed per command. Free: 500,000 commands a month and 250 MB. Polling or a check on every request can use the month's commands within days.
Free cluster, 512 MBMongoDB Atlas (free cluster)
Hosted MongoDB. The free cluster holds 512 MB and is paused after 30 days with no connections. MongoDB offers it for learning, not for production, and the Student Pack adds $50 of credit.
Free software, you hostPocketBase
A one-file open-source backend with SQLite, sign-in, file storage and an admin screen. The software is free but you host it on a server with a persistent disk, and its docs say it is not yet recommended for production-critical apps.
Compare in a table
Show the full comparison table
| Tool | Best for | Free plan |
|---|---|---|
| Supabase | First app with logins | Free plan, 2 projects |
| Firebase | Flutter and Android apps | Spark plan, no card |
| Neon | Postgres for Next.js apps | Free plan, no card |
| Turso | Tiny apps, many databases | Free plan, no card |
| Convex | Live data without SQL | Free plan |
| Appwrite Cloud | Open-source backend | Free plan, 2 projects |
| Cloudflare D1 and KV | Small SQL for Workers apps | Free daily limits |
| Upstash Redis | Rate limits and caching | Free plan, 1 database |
| MongoDB Atlas (free cluster) | MERN stack projects | Free cluster, 512 MB |
| PocketBase | Self-hosted backend | Free software, you host |
Get started this week
- Create a free Supabase project and one table with a user_id column.
- Turn on row-level security and add a policy so each user sees only their own rows.
- Sign in as two test users and confirm neither can read the other's data.
How to choose
- Start with Supabase if your app builder offers it; most AI builders generate code for it.
- Turn on row-level security for every table before you share the link; a public key without it exposes your data.
- Choose Neon or Turso when you want a plain database and will write your own sign-in.
- Take your own backup on any free plan that does not keep one, and read the pause rule before a demo.
Free plans change. Limits above were checked on 3 Nov 2026; confirm on each tool's pricing page before relying on them.
Frequently asked questions
What is the best free backend for a vibe-coded app?
Supabase for most first apps, because it bundles Postgres, sign-in and storage and is the backend most AI app builders generate code for. Use Firebase if you build in Flutter or for Android.
Do free Supabase projects get deleted?
They are paused after a week of low database activity, not deleted. You can restore a paused project from the dashboard, but the free plan has no automatic backups, so export your data before an important demo.
Is Firebase free for students?
The Spark plan needs no card and covers Authentication and Firestore within limits. Cloud Storage and Cloud Functions need the Blaze plan, which needs a card, so check before you pick it.
What happens to my app when the free limit is reached?
It depends on the service. Neon suspends compute, Cloudflare D1 queries fail until midnight UTC, and Appwrite projects freeze read-only. None delete your data, but your app stops working until the limit resets or you upgrade.
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