Contentful to Sanity Migration: When and How

A Contentful to Sanity migration exports content types, entries, and assets through Contentful's APIs, remodels them as Sanity schemas defined in code, transforms rich text into Portable Text, imports the result via Sanity's import tooling, and verifies parity against a documented baseline — usually motivated by editorial customization needs rather than platform failure. That last clause matters more than any technical detail below, so this guide starts with whether the move is justified at all.

First: Should You Migrate at All?

There are legitimate reasons to move. The strongest is editorial customization: Sanity Studio is a React application you own and extend, so if your editors need custom input components, workflow-specific views, or an authoring interface embedded directly inside your own product, that is something you build rather than configure. Close behind is schemas-as-code — content model changes arrive as pull requests, get reviewed, and move through environments the way the rest of your codebase does. Cost model fit is a real reason too, particularly for teams that need many editor seats or whose usage sits awkwardly against per-space plan boundaries.

What is not a legitimate reason: vague dissatisfaction. Contentful is a mature, capable, well-supported platform with a strong API surface, genuinely good localization handling, and enterprise governance features that many teams depend on. If the current pain is a badly designed content model, migrating will carry that model to a new platform intact. Fix the model first; you may find the platform was never the problem. If you are still deciding between the two, our Sanity vs Contentful comparison covers the trade-offs in full, and the platform selection guide works through the decision without assuming an answer.

Why This Migration Is Different

Most migration advice you will read is written for moves off WordPress or another page-oriented CMS, where the central problem is that content does not have a structure yet — it is HTML with shortcodes in it, and the work is inventing a model that never existed. A Contentful to Sanity move is headless-to-headless, and the content is already structured. The work shifts from restructuring to translation.

• Content types become schemas. Both platforms model content as typed documents with defined fields, so the mapping is largely one-to-one — expressed in Contentful's UI on one side and in TypeScript on the other.
• References become references. Relationships between entries survive the move as relationships between documents; the work is preserving identity so nothing dangles after import.
• Rich Text becomes Portable Text. Both are structured JSON rather than HTML strings, so this is a node-by-node transform, not a parse-and-hope conversion.
• Locales become localized fields. Contentful's locale system and Sanity's localization patterns solve the same problem differently, so this needs a deliberate design decision rather than a mechanical mapping.

The practical consequence is the biggest scope reducer available to you: if your frontend is already a headless application — a Next.js site consuming the Contentful Delivery API — the components, routing, and design system usually survive untouched. Only the data layer is rewritten. Establish whether that is true of your site before scoping anything else, because the difference between "rewrite the data layer" and "rebuild the frontend" is the difference between two very different projects.

The Five Phases

Those phases are the migration-specific expression of the documented-baseline, side-by-side-comparison, instrumented-launch process we publish in our methodology. The discipline does not change with the destination platform; only the translation layer in the middle does.

What Actually Goes Wrong in These Migrations

• Rich Text edge cases. This is the hard part, and it is worth saying plainly: headings and lists convert trivially, but embedded entries and embedded assets inside Rich Text are where these projects actually get stuck. Each embed type needs a Portable Text block type, a schema, and a frontend renderer — and the inline variants (an entry referenced mid-sentence rather than as its own block) are the ones teams forget until a page renders with a hole in it.
• Locale handling. Contentful localizes at the field level within a single entry. Sanity offers several patterns — localized field objects, separate documents per language, or a document-level translation reference — and the choice affects querying, editing, and routing. Deciding this during the transform script instead of during design is how teams end up migrating twice.
• Asset URL rewrites. Assets keep working right up until the old space is decommissioned, which makes it very easy to ship with images still served from Contentful's CDN. Every asset reference — including the ones buried inside Rich Text nodes and inside plain-text fields as hardcoded URLs — has to be rewritten and verified, not assumed.
• Unmapped webhooks and integrations. Contentful spaces accumulate webhooks, scheduled publishes, preview configurations, and app integrations that nobody documented. They are invisible in a content export and only surface when something silently stops firing after cutover. List them during inventory and map each one to its Sanity equivalent or an explicit decision to retire it.
• Un-repeatable imports. A hand-corrected, one-shot import means the rehearsal was the performance, and any content published during the project is stranded. Scripts must run cleanly from scratch against fresh content, every time.

What You Gain on the Other Side

A content model that lives in your repository, reviewed like code and versioned with it; an editing environment you can shape to your editors instead of configuring around; and GROQ queries that shape responses at the API rather than in application code. The structural benefit that matters most for search is that typed documents with real references map cleanly onto schema.org markup — the entity-level clarity that classic search and AI answer engines both reward, and the foundation of the entity SEO work we specialize in. That said, Contentful models content as typed documents too; the gain here is in ownership and extensibility, not in structure you did not already have.

If you want the build side rather than the decision side, our Sanity development page covers schema design, Studio customization, and frontend integration. Webvello is an independent development partner and is not affiliated with Sanity Inc. or Contentful.

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