Convex vs Supabase vs Firebase: the Next.js backend call (2026)

Quick answer (2026): For a Next.js app, the backend choice is really a choice about your data model and how much of it you own. Supabase is a Postgres backend you own: real SQL, open-source (Apache-2.0), self-hostable, portable. Firebase is Google's proprietary NoSQL: the fastest zero-to-live, realtime by default, and the most locked-in. Convex is a typed, reactive TypeScript backend with the best developer experience of the three, source-available under a restricted license, with no general-availability self-host. Pick Supabase to own your data, Firebase to ship fastest, Convex for end-to-end typed reactivity.

We test a lot of starters here, and the backend is the one decision that is expensive to undo. Swap a UI library on a Saturday. Swap your database and you are rewriting queries, auth, and half your API. So it is worth slowing down for a paragraph.

The mistake most comparisons make is treating these three as interchangeable "backend-as-a-service" boxes and then arguing about price. They are not interchangeable. They are three different bets on how your data is shaped and who holds the keys.

The three bets at a glance

Here is the whole decision in one table, with every star, license, and price cell sourced from the vendor's own pages in July 2026.

Supabase: own your data

Supabase is the "own it" option. Under the hood it is plain PostgreSQL with auth, storage, edge functions, and an opt-in Realtime layer wrapped around it. The codebase is genuinely open: Supabase's repo is Apache-2.0 with about 106k stars and a July 2026 developer update, and you can self-host the whole thing on your own metal.

That is the real reason to pick it. Your schema is standard Postgres, so your data is portable and your SQL skills transfer. If Supabase ever raises prices or you outgrow it, leaving is a pg_dump, not a rewrite.

The free plan, per Supabase's pricing page, gives you a 500MB database, 1GB file storage, 5GB egress, and 50,000 monthly active users across a maximum of two projects. The gotcha that catches side projects: free projects are paused after one week of inactivity. Pro starts from $25 a month and lifts you to 100,000 MAU, 8GB of disk, 250GB egress, and daily backups kept for seven days. If you have already decided you just want managed Postgres without the rest of the platform, we compared Neon and Supabase as Postgres hosts separately.

Firebase: ship the fastest

Firebase is the "rent it, and go now" option. It is Google's mature, proprietary platform built around Firestore, a NoSQL document store that is realtime out of the box, plus auth, hosting, and a deep bench of extras like Crashlytics and Cloud Messaging. For a web-and-mobile app that needs live data on day one, nothing gets you there faster.

The trade is ownership. There is no public repository and no self-host path, so Firebase is a one-way door: your data lives in Google's cloud in a proprietary shape, and migrating off is a rewrite, not an export.

The free Spark plan, from Firebase's Spark and Blaze plans, looks generous: 1 GiB of Firestore storage, up to 50,000 authenticated users, 10GB of hosting. But read the throughput line, because it is the one that bites. Spark caps you at 50,000 document reads per day, 20,000 writes, and 20,000 deletes. A chatty realtime dashboard with a few hundred active users can blow through 50,000 reads a day, at which point you are on Blaze, Google's pure pay-as-you-go tier where the bill tracks Google Cloud rates. It is the least predictable cost of the three because there is no flat plan to sit on.

Convex: typed and reactive

Convex is the newest bet and, for a lot of Next.js teams, the most fun to write. It is a reactive backend where you write your queries and mutations as TypeScript functions, and the client subscribes to them with full end-to-end types. Realtime is the default, not a feature you wire up. The backend is source-available: Convex's open-source backend is about 12.2k stars, written in TypeScript and Rust.

Read the license carefully, because "open source" is doing some work in most write-ups. Convex ships under FSL-1.1-Apache-2.0, the Functional Source License. You can read, modify, and self-host the code for your own use, but you cannot offer a competing hosted Convex. The nuance most comparisons miss: that restriction auto-expires, and each release converts to plain Apache-2.0 two years after it ships. It is source-available today, genuinely open on a delay.

Pricing, from Convex's pricing: the free Starter plan covers 1 million function calls, 0.5GB of database storage, and 1GB of file storage for up to six developers, then bills pay-as-you-go. Professional is $25 per developer per month with 25 million function calls and 50GB of storage. Note the shape: Convex charges per developer, so a three-person team starts at $75 a month before usage, where Supabase Pro is closer to flat. If you want the hands-on version, our Convex starter review walks through building on it.

Where each one loses

No backend wins on every axis. The honest cons:

• Supabase is not realtime by default, so live features are opt-in work. The free tier pauses after a week, and Postgres connection pooling takes some care on serverless Next.js.
• Firebase is proprietary with no self-host, NoSQL modeling gets awkward for relational data, and the 50,000-reads-per-day free cap plus Blaze's usage billing can surprise you.
• Convex is FSL rather than truly open, has no general-availability self-host, prices per developer as your team grows, and has the smallest ecosystem and community of the three.

Which situation picks which

The r/nextjs regulars argue this out in one long r/nextjs thread, and the consensus roughly matches the math:

1. You want to own your data, write SQL, and keep the option to self-host or leave: Supabase.
2. You need live data on web and mobile as fast as possible and Google lock-in is acceptable: Firebase.
3. You are a TypeScript-first team who wants reactivity and the best developer experience, and a young ecosystem plus a restricted license is a fair trade: Convex.

There is no wrong answer here, only a wrong fit. Match the backend to the shape of your data and your tolerance for lock-in, and any of the three will carry a real product.

Your move: before you write a single query, write down the one thing you cannot afford to lose in a migration. If it is your data, pick Supabase. If it is your launch date, pick Firebase. If it is your developer velocity, pick Convex.