Your application can have a perfectly working database and still have a serious security problem if users can access records they shouldn't. Row Level Security, commonly called RLS, helps solve this at the PostgreSQL level.
What Is RLS?
RLS allows database policies to determine which rows a user can access.
Instead of saying:
“Authenticated users can read this entire table,” you can define a rule such as: “Users can read only rows belonging to their own account.”
Enable RLS
Open the relevant table in Supabase and enable Row Level Security.
Once enabled, review which operations your application needs.
Create Policies
Policies can control operations such as:
SELECT INSERT UPDATE DELETE Test the Rules
Testing is critical.
Create multiple users and verify that each user sees only the data they should see.
Don't Disable RLS Just to Fix an Error
During development, it can be tempting to disable security when a query fails.
Instead, understand which policy is blocking the request and create the correct rule.
RLS is one of the most important Supabase features for applications that expose database data directly to users.