A blog by Elisabeth Escribano, Software Architect at Youwe
First of all, there are different terms used. Some people talk about a headless CMS and others talk about a decoupled CMS, but these terms are synonyms. So, they are exactly the same! With a traditional CMS, the Content Management Systems controls both the backend and the frontend. So, if you, for example, are using Drupal as a CMS then Drupal has complete control over the presentation and data layers. When you choose for a headless approach. Then the CMS has control over the data layers but has no responsibility for how the data is presented. In a headless approach, the frontend is decoupled from the backend.
With a headless CMS, you also have different kinds of versions of decoupled systems. You can progressively decouple or fully decouple.
When you are not entirely sure if a headless approach is the right solution for you then an in-between solution is to progressively decouple. This means that your CMS for example Drupal is still partially responsible for the presentation layer, but JavaScript is required to offer the interactive user experience that is desired. In this scenario, the JavaScript framework is layered on top of the existing CMS front end. The responsibility of JavaScript is limited in this case.
The other choice is to fully decouple. Then the CMS is purely the data provider. The JavaScript framework is solely responsible for the presentation. This means that all rendering and markup are communicating with the CMS via web services or APIs. The great benefit of a headless approach is that one JavaScript framework can be used for different data providers. This is because, as said as earlier when you chose a headless approach, the frontend and backend are decoupled from each other.
So, now the big question is: “Should I stay at my traditional CMS, or should I choose for a headless CMS? This all depends on your requirements, purpose, long term plans and budget. It is not an easy decision to make. And there are pros and cons either way. The following points will hopefully make your decision a bit easier.