Convex vs Supabase is the backend choice that decides how much control you keep versus how fast you can ship. Both are modern, serverless-friendly platforms, but they solve different problems.
I've spent time building with both, and the confusion is fair — they look similar from the outside. Both give you a database, real-time subscriptions, and auth. But once you write your first query, the difference snaps into focus. Convex is a reactive backend that treats your database as a cache; Supabase is a Postgres database with a real-time layer bolted on.
Convex vs Supabase: The Key Differences
The core difference is the data model and the execution model.
Convex is built around reactive queries. You write TypeScript functions that query the database, and Convex automatically re-runs them when the underlying data changes. The client subscribes to those queries, and the UI updates instantly. There's no REST endpoint to hit, no GraphQL schema to maintain — just functions.
Supabase is Postgres first. You get a full SQL database, Row Level Security (RLS), and a PostgREST API that auto-generates REST endpoints from your schema. Real-time is a separate feature you enable on specific tables. You write SQL for complex queries, and you manage migrations with SQL files.
Here's the concrete difference in code. In Convex, a query is a function:
// convex/getTodos.ts
import { query } from "./_generated/server";
export const getTodos = query({
handler: async (ctx) => {
return await ctx.db.query("todos")
.filter((q) => q.eq(q.field("completed"), false))
.collect();
},
});
The client subscribes to it reactively:
// client.ts
import { useQuery } from "convex/react";
function TodoList() {
const todos = useQuery(api.getTodos);
return todos.map(todo => <div key={todo._id}>{todo.title}</div>);
}
In Supabase, you write SQL and fetch via the client:
// client.ts
import { createClient } from "@supabase/supabase-js";
const supabase = createClient(URL, KEY);
async function getTodos() {
const { data } = await supabase
.from("todos")
.select("*")
.eq("completed", false);
return data;
}
For real-time in Supabase, you subscribe to a channel. In Convex, it's automatic.
When to Use Convex
Use Convex when your app is state-heavy and interactive — think collaborative tools, live dashboards, or any UI where the same data appears in multiple places.
Convex shines when you need to react to changes instantly without wiring up websockets or managing cache invalidation. The reactive model eliminates the "stale data" problem by design. If you're building a kanban board where cards move between columns, Convex handles the multi-user sync without you writing a single line of WebSocket code.
Convex also wins when you want to keep all your logic in TypeScript. There's no SQL, no separate API layer — just functions that run on the server. This is a huge productivity boost if your team is TypeScript-only.
When to Use Supabase
Use Supabase when you need full SQL power or when you're building on top of Postgres-specific features.
If you're doing complex aggregations, window functions, or heavy reporting, SQL is the right tool. Supabase gives you the entire Postgres ecosystem: extensions like PostGIS for geospatial data, full-text search, and mature tooling for backups and migrations.
Supabase is also the better choice if you have an existing Postgres database you want to move to the cloud, or if you want to leave the door open to migrate to a self-hosted Postgres later. The data layer is standard and portable.
Convex or Supabase: Which One Should You Pick?
Pick Convex if your app is real-time-first and you want to avoid managing sync logic. Pick Supabase if you need SQL for complex queries, or if you want to stay close to standard Postgres tooling.
The deciding question is: do you need arbitrary SQL, or do you need automatic reactivity? If you find yourself writing complex JOINs and window functions, Supabase is the answer. If you're tired of writing cache invalidation and WebSocket handlers, Convex is the answer.
My Take
I lean Convex for new greenfield apps that are interactive and client-heavy. The reactive model removes a whole class of bugs I've hit with Supabase — stale caches, missed subscriptions, and race conditions between optimistic updates and server state.
But I'd pick Supabase in a heartbeat for anything with serious reporting or analytics needs. SQL is unbeatable for those workloads, and Convex's query API, while expressive, isn't a replacement for a well-tuned SQL query.
The one thing that makes this decision obvious: if you can describe your data as "state that changes and must be reflected everywhere," use Convex. If you can describe it as "rows that need to be queried in complex ways," use Supabase.