Building a blog with React and Next.js is one of the most common use cases for modern web development. But where you store and manage your content matters just as much as the frontend you choose. In this tutorial, you'll learn how to build a fast, production-ready React blog using the Next.js App Router and Cosmic as your headless CMS. Want to skip ahead? Grab the free Simple React Blog template and deploy in minutes. Why Use a Headless CMS for a React Blog? Managing blog content directly in your codebase works fine for a handful of posts, but it breaks down fast. Markdown files scattered across a repo, no visual editing interface, and every content update requiring a developer and a deployment are all pain points that accumulate quickly. A headless CMS solves this by separating your content layer from your presentation layer. You manage posts, authors, and categories in a structured dashboard. Your Next.js app fetches that content via the REST API at build time or on demand.…