Three terms – one misunderstanding
"We're going headless," "we want composable," "we're building MACH-compliant"—these often mean the same thing, yet the three terms describe different levels. Those who clearly distinguish between them make better architectural decisions and avoid inadvertently purchasing complexity they’ll never need. In a nutshell: Headless is the prerequisite, MACH is the engineering discipline, and Composable is the business outcome.
Headless
"Headless" means that the front end (the "head") is separated from the back end. Content and data are delivered via an API, and the presentation is decoupled from it and can be freely chosen. A headless CMS like DatoCMS delivers structured content—whether that becomes a website, an app, or a display screen is determined by the frontend. Headless is a characteristic of a single system.
DO
MACH stands for four principles: microservices, API-first, cloud-native, and headless. The term was coined in 2020 by the MACH Alliance—a consortium of providers such as commercetools, Contentstack, and Algolia. MACH describes the design principles: interchangeable, independently deployable best-of-breed components.
Composable
Composable is what you get when you build according to MACH principles: a stack of modular components that can be slotted together like Lego. Instead of a single suite, you use a best-of-breed set—such as DatoCMS for content, Shopify or commercetools for the store, Algolia for search, and Stripe for payments. Each component can be replaced individually.
A concrete example stack
A composable architecture for an online store might look like this: DatoCMS (content) + commercetools (commerce engine) + Algolia (search) + Stripe (payment) + a Nuxt or Astro frontend that brings everything together via APIs. If the search provider falls out of favor, you can swap Algolia for a competitor—the rest remains unaffected. That is precisely the difference from a monolith, where changing a module triggers a replatforming.
Headless alone is sufficient for a decoupled website that needs to be fast and support multiple channels. MACH and Composable are worthwhile as soon as multiple specialized systems need to work together, teams need to operate independently, and individual components need to be interchangeable over time.
Conclusion
These three concepts are not competing ideas, but rather different levels of the same concept: decoupling systems (Headless), building according to clear principles (MACH), and assembling a flexible stack from them (Composable). The right question is never “headless or composable?”, but rather “how much flexibility does my business really need?”.