Supabase Auth + Row Level Security: The Complete Guide

If you're building a multi-user SaaS product, Row Level Security (RLS) is one of the most important security features you can implement. Here's why — and how to do it with Supabase and Next.js.

What is Row Level Security?

RLS is a PostgreSQL feature that enforces access control at the database level. Instead of relying on your application code alone to filter data by user, the database itself refuses to return rows the user doesn't own.

That means even if there's a bug in your API route — a missing WHERE clause, a broken authorization check, a subtle injection issue — the database still prevents cross-tenant data leakage. It's defense in depth, and for SaaS it's not optional.

Why Application-Level Auth Isn't Enough

Consider an API route that returns a user's conversations. Application-level filtering works until it doesn't: a refactor, a rushed feature, or a malicious request can expose data you never intended to return.

With RLS, PostgreSQL adds the tenant filter automatically. Even if a query is overly broad, each session only sees rows that policies allow.

Setting Up RLS with Supabase

Supabase makes RLS approachable:

1. Enable RLS on every table that holds user data.
2. Write policies that tie rows to auth.uid() (or your tenant model).
3. Test with real JWTs — not just service role keys.

The typical pattern for a SaaS app: users can SELECT, INSERT, UPDATE, and DELETE their own rows, usually by matching auth.uid() to a user_id column.

For shared resources (teams, workspaces), policies check membership through join tables. The principle stays the same: the database decides what crosses the wire.

RLS with Drizzle ORM

When using Drizzle ORM (which Ignitra uses), your queries look like normal SQL from the app's perspective. The ORM generates standard queries; PostgreSQL applies RLS policies transparently. You get security without rewriting your mental model for every query.

Common Mistakes

1. Creating a table and forgetting to enable RLS — In Supabase, tighten this immediately; don't ship with open tables.
2. Overly permissive policies — Start strict; loosen deliberately.
3. Testing only with the service role — Service role bypasses RLS; always verify as an authenticated user.

Ignitra ships with RLS-oriented patterns for conversations, messages, usage, and user-scoped data — so you're not inventing policy structure from scratch.

For auth setup specifics, see our Authentication guide. If you're comparing foundations, buy vs build is worth a read too.

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Security isn't a sprint after launch — it's the foundation. Ignitra pairs Supabase Auth with SaaS-friendly patterns so you can ship confidently. Documentation.