Lovable Security Best Practices: Secure Your GPT Engineer Apps

How Lovable Handles Security

Lovable (formerly GPT Engineer) builds a complete web application from a description, usually React with a Supabase backend. It's very good at the part you can see. The security configuration is mostly left to you.

Defaults have improved over time. They still aren't a substitute for checking, and the checking is what this page is for.

Best Practice 1: Export and Review Your Code 10 min

Lovable can push your project to GitHub. Do it regularly, and actually read what lands there. You're looking for six things:

What to Look For in Exported Code

Security review checklist:

• No hardcoded API keys or secrets in source files
• Supabase client uses environment variables
• Authentication checks on protected components
• Input validation on forms and API calls
• Proper error handling without exposing details
• CORS configured correctly if using external APIs

Best Practice 2: Secure Supabase Integration 10 min

Most Lovable apps sit on Supabase, which means your database is reachable from the browser by design. Row Level Security is what decides whether that's fine or a problem.

Enable Row Level Security

-- Protect user profiles
ALTER TABLE profiles ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Users can view own profile"
ON profiles FOR SELECT
USING (auth.uid() = id);

CREATE POLICY "Users can update own profile"
ON profiles FOR UPDATE
USING (auth.uid() = id);

-- Protect user-created content
ALTER TABLE user_content ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Users manage own content"
ON user_content FOR ALL
USING (auth.uid() = user_id);

Verify RLS is Working

1. Open your Supabase dashboard
2. Go to Table Editor
3. Check that each table shows "RLS Enabled"
4. Review the policies for each table
5. Test by trying to access data you should not have access to

Best Practice 3: Secure Authentication Flow 10 min

Lovable normally wires up Supabase Auth for you. It's worth reading that code rather than assuming it, because the two places auth has to hold are the page and the query, and only one of them is visible.

// Good: Check auth state before rendering protected content
function ProtectedPage() {
  const { user, loading } = useAuth();

  if (loading) return <LoadingSpinner />;
  if (!user) return <Navigate to="/login" />;

  return <DashboardContent />;
}

// Also protect API calls
async function fetchUserData() {
  const { data: { session } } = await supabase.auth.getSession();

  if (!session) {
    throw new Error('Not authenticated');
  }

  return supabase
    .from('user_data')
    .select('*')
    .eq('user_id', session.user.id);
}

Best Practice 4: Validate All User Inputs 10 min per form

Generated forms tend to validate for shape, not for safety. Add a schema so the server never sees something you didn't expect.

import { z } from 'zod';
import { useForm } from 'react-hook-form';
import { zodResolver } from '@hookform/resolvers/zod';

const schema = z.object({
  title: z.string()
    .min(3, 'Title must be at least 3 characters')
    .max(100, 'Title too long'),
  description: z.string()
    .max(500, 'Description too long')
    .optional(),
  email: z.string()
    .email('Invalid email address'),
});

function MyForm() {
  const { register, handleSubmit, formState: { errors } } = useForm({
    resolver: zodResolver(schema)
  });

  const onSubmit = (data) => {
    // Data is validated and typed
    saveData(data);
  };

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      {/* Form fields */}
    </form>
  );
}

Best Practice 5: Secure Third-Party Integrations 5 min per integration

Every integration you add is another key that has to live somewhere. The question each time is whether it can survive being in the browser.

Best Practice 6: Configure Deployment Security 10 min

Two things to settle before the app is public.

Environment Variables

• Set production environment variables in your hosting dashboard
• Never commit .env files to your repository
• Use different keys for development and production

HTTPS and Headers

• Verify HTTPS is enabled (most hosts do this automatically)
• Add security headers if your host supports them
• Configure Content Security Policy for production

Best Practice 7: Monitor and Maintain Ongoing

Launching isn't the finish line. Four habits worth keeping:

• Monitor Supabase usage: Watch for unusual query patterns
• Update dependencies: Export to GitHub and run npm audit periodically
• Review access logs: Check for failed authentication attempts
• Test authentication: Periodically verify login/logout works correctly

Common Lovable Security Mistakes