Building a SaaS Admin Dashboard With Next.js 14: Users, Metrics, and Feature Flags

Every SaaS needs an admin interface -- a place to see all users, manage subscriptions, toggle feature flags, and view key metrics. Most devs build it too late or not at all. Here's a practical admin dashboard built with Next.js 14. Architecture app/ admin/ layout.tsx # Admin auth check, nav sidebar page.tsx # Overview metrics users/ page.tsx # User list with search/filter [id]/page.tsx # Individual user detail subscriptions/ page.tsx # Active subscriptions flags/ page.tsx # Feature flag management Admin Auth Guard // app/admin/layout.tsx import { auth } from '@/lib/auth' import { redirect } from 'next/navigation' import { db } from '@/lib/db' export default async function AdminLayout({ children }) { const session = await auth() if (!session?.user?.id) redirect('/login') const user = await db.user.findUnique({ where: { id: session.user.id } }) if (user?.role !== 'admin') redirect('/dashboard') return ( <div className='flex h-screen'> <AdminSidebar /> <main className='flex