Glossary
Headless CMS
A headless CMS is a content management system that delivers content via API without dictating how it's rendered. Frontends are built separately, typically with React, Vue, or other modern frameworks.
Traditional CMSes (WordPress, Drupal, Joomla) bundle content management + theming + rendering into one system. The CMS controls how the site looks AND how the content is stored. Headless CMSes split this: content is stored in a database accessible via REST or GraphQL API; the frontend is a separate codebase that fetches content and renders however it wants.
Popular headless CMS options: Contentful (enterprise-tier pricing), Sanity (developer-favorite, generous free tier), Strapi (open-source self-hosted), Hygraph (GraphQL-first), Storyblok (visual editor-friendly), Prismic (block-based editing), WordPress in headless mode (using its REST/GraphQL API).
Why headless matters for SEO: it decouples content from presentation, letting you build a modern, fast frontend (Next.js, Astro) while editorial teams still get a familiar CMS. The frontend can be optimized for Core Web Vitals, schema, and rendering speed in ways traditional CMSes struggle with (WordPress' page-builder plugins generate heavy DOMs).
Headless workflow: a writer creates a post in the CMS UI. The CMS stores the content. The frontend's build process (or ISR webhook) regenerates the affected pages. Visitors see the updated content. This is the modern Jamstack pattern.
Tradeoffs: more engineering work to set up than traditional CMS. Two systems to maintain (the CMS and the frontend) instead of one. Cost — headless CMS pricing typically starts at $0-25/mo for small projects and scales to $1,000+/mo for enterprise (vs WordPress's free + hosting cost). The payoff is speed, flexibility, and the ability to serve content to multiple frontends (website, mobile app, marketing site, partner portal) from one source.
Example
A SaaS team uses Sanity (headless CMS) for blog content and product copy. Marketing edits posts in Sanity's UI. The Next.js frontend fetches content via Sanity's GraphQL API at build time + uses ISR to regenerate when posts are published. Lighthouse Performance is 96; editing experience is similar to WordPress; bundle size is half of an equivalent WordPress + Elementor setup.