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 ' > < Adm