Bolt.new + Next.js + Supabase Security Blueprint

To secure a Bolt.new + Next.js + Supabase stack, you need to: (1) use the correct Supabase client type for each Next.js context (browser vs server vs middleware), (2) add authentication verification to all Server Actions using auth.getUser(), (3) enable RLS on all Supabase tables, and (4) configure middleware to protect authenticated routes. This blueprint covers the unique security challenges of combining Next.js App Router with Supabase.

Setup Time2-3 hours

TL;DR

Next.js App Router requires different Supabase clients for different contexts. Bolt-generated code often mixes these up or skips auth verification in Server Actions. After export: verify correct client usage, add auth checks to all Server Actions, enable RLS on all tables, and configure middleware for protected routes.

Supabase Client Types

Context	Client	Common Issue
Client Components	createBrowserClient	May use server client
Server Components	createServerClient	May skip cookie handling
Server Actions	createServerClient	Often missing auth check

Part 1: Next.js Server Action Security

SECURE: With auth verification

'use server'

import { createClient } from '@/lib/supabase/server'

export async function updateProfile(formData: FormData) {
  const supabase = await createClient()

  const { data: { user }, error } = await supabase.auth.getUser()

  if (error || !user) {
    throw new Error('Unauthorized')
  }

  await supabase.from('profiles').update({
    name: formData.get('name')
  }).eq('id', user.id)  // Use verified user ID

  return { success: true }
}

Critical: Always use auth.getUser() in Server Actions. Never trust user IDs from form data.

Security Checklist

Post-Export Checklist for Bolt + Next.js + Supabase

Correct Supabase client for each context

RLS enabled on all tables

Auth verification in all Server Actions

Middleware protects authenticated routes

User ID from auth.getUser(), not client

Service role key only in server code

Alternative Stacks to Consider

      **Bolt.new + Supabase**
      General Supabase security guide


      **Bolt.new + Supabase + Vercel**
      Complete deployment security


      **Bolt.new + React + Firebase**
      Firebase alternative stack

Why do I need different Supabase clients?

Next.js runs code in different environments. Each handles cookies and auth tokens differently. Using the wrong client causes auth state mismatches.

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