What is a Headless CMS

A classical CMS provides a way to author content and a way to render that content as web-pages. A headless CMS provides content authoring but instead of web-page-rendering, it provides the content as data over an API. You then write one or more front-ends that present the content to end-users. The front-ends can be web-sites, apps, voice assistant skills, e-book generators, games etc. The grand idea is that when content is pure data, presentation modes can evolve independently of the content authoring.

A fair question then would be: what's the big deal? Can't you just stick an API on Wordpress and off you go? That leads to the other, less obvious difference: A good headless CMS is focused on authoring the content as structured data so that it is clear to the presentation layer what each piece of information means. Take this fact-box from a project page on the (Sanity powered) site:

The map, timeline and bar chart here is rendered on the front-end based on geo-positions, lists of milestones and area-usage authored by the OMA editors. In their old CMS these would be authored as images and html-fragments, but with Sanity it is described as a structure of data-points with a defined meaning. This allows us to use those same data-points to provide an advanced search (give me buildings with 20-30% office space and more than 15% retail), and it has also allowed us to generate books from the exact same dataset that power their web-site.

So, the big hairy goal of a headless CMS is to disentangle the content from its presentation, thereby making the content reusable across many forms of presentations ultimately making the work spent authoring that content more valuable.

Previous: QuickstartNext: The Sanity Way