Buyer guide
Headless CMS: when you need one
Knut Melvær at Sanity has written the sentence agencies skip: you should not build a CMS for a site whose authors already live in git. He points at markdown-in-a-repo as the correct tool when the whole team writes code, the content has one destination, and you publish rarely enough that a pull request is fine. A personal blog is his counterexample. A marketing team that must not be asked to commit is the case for a CMS.
Written by SiteMivo. Sanity, Payload, and Contentful are options, not a ranking. Drafted with research assistance.
Editors and a cadence, or you are renting a second git
If the only person who changes copy is the person who deploys, keep the copy next to the components. You already have review, history, and a rollback. A CMS in that setup is another login, another bill, and a preview environment that drifts from the branch you shipped.
The model lives in the repo. The documents live in the CMS.
Sanity declares the schema in the Studio repo. Payload’s config is code in the app, which is why James Mikrut argued for installing it in the same repository instead of running a second service that deploys on a different day. Contentful keeps content types in a Space, and still expects a developer to design that model. Routes, components, and the fields that become the title and the meta description stay in code. Editors change documents. They do not invent a new URL shape on a Friday.
One fact, one place, and the account in your name
Melvær’s later note on agents names the failure you will actually hit: a price written in five places and right in three. The CMS becomes a second source of truth the moment the live page and the document disagree, and nobody knows which one the customer saw. Put the price, the legal line, and the offer in one document. Everything else references it.
The CMS organisation, the billing contact, and the editor invites sit in your account, not ours. Sanity Manage, a Payload user collection in your database, or a Contentful organisation owner: same rule. If we leave, you can still publish.
Melvær, 2025, Mikrut, 2023, Contentful modelling.
Custom websites start without a CMS unless the brief names an editor who is not a developer.