Headless CMS Showdown: insights from the Light Up Tech Conference
At the Light Up Tech Conference, we brought together four iO experts for an open panel discussion on headless CMS platforms. No pitches. No competition. Just an honest conversation about different visions, approaches, and real-world use cases.
The panel featured:
Jori Regter — Technology Director & Sanity expert
Leon Stemerdink — Solution Architect & Contentstack expert
William Parr — Tech Lead & Optimizely expert
Rob Habraken — Technology Director & 10x Sitecore MVP
The key takeaway?
There is no such thing as the best headless CMS. The right choice depends entirely on what you want to achieve with your content.
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What do we mean by “headless”?
While vendors add their own nuances, there’s one shared definition.
A headless CMS separates the back end (content) from the front end (presentation) and delivers content via APIs. In practice, that means:
A back end decoupled from the front end
Freedom to choose your preferred frameworks
Content that works across multiple channels
Faster innovation without rebuilding your CMS
Headless isn’t just a technical choice. It’s about flexibility, and how freely you want to use and reuse your content.
The experts on the panel each shared their insights based on their own expertise, discussing the possibilities within their CMS in various areas: content structure, customisability, and DXP & personalisation with AI.
Content structure: from pages to building blocks
The biggest shift with headless CMS is moving away from page-based thinking. Traditional CMS platforms revolve around pages and tree structures. Headless platforms focus on reusable content components.
That said, platforms differ in how much structure they enforce.
Sanity
Sanity positions itself as a Content Operating System. Everything is configurable through code. You’re not tied to pages or URLs: content can power a website, a mobile app, a stadium screen, or even a live broadcast.
A concrete example discussed during the panel was live sports content:
A live blog in a mobile app
Push notifications when a goal is scored
Instant replays streamed to TV via the app
Same content. Multiple channels. Real-time publishing.
Contentstack
Contentstack also fully decouples content from website structure. The content model is central, not a site tree. Content is delivered via REST or GraphQL to any channel.
Their philosophy is clear: content should work anywhere, in any format, without the website structure dictating how it’s used.
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Optimizely
Optimizely combines structured content management with headless delivery. There’s still a clear organizational framework, but content is published omnichannel.
With tools like the Visual Builder and the Opal AI assistant, editorial teams are supported in creating and managing content within that structure.
Sitecore
Sitecore maintains a familiar tree structure, including built-in page routing and multilingual support. At the same time, content can be distributed headlessly to other channels.
This makes Sitecore an attractive option for organizations transitioning from a traditional CMS to a headless approach.
All four platforms support omnichannel delivery. The real difference lies in how much freedom versus editorial guidance you want in your content structure.
Customizability: how much control do you want?
A common assumption is that SaaS CMS platforms are less flexible. The panel showed the opposite: modern SaaS platforms offer plenty of customization. It just works in different ways.
Sanity
Sanity is SaaS, but Sanity Studio is open source. You can customize not only content models, but also the editorial interface itself.
With plugins, custom apps, and framework-agnostic integrations, Sanity offers exceptional flexibility for development teams.
Contentstack
Contentstack provides an extensive marketplace with integrations for DAM, search, and marketing tools. Their Automate engine allows teams to streamline workflows using “if-this-then-that” logic, with AI playing an increasingly important role.
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Optimizely
Depending on the setup, Optimizely supports customization through features like a Modeling API, external content sources, and headless forms.
The traditional line between PaaS (more control) and SaaS (less control) is fading as SaaS platforms become more extensible.
Sitecore
Sitecore XM Cloud supports customization through custom widgets from the Marketplace, webhooks, and an Authoring API. This allows developers to connect content workflows with other systems and data streams.
Modern SaaS CMS platforms are far less closed than they used to be. Today, flexibility lives in APIs, extensions, and integrations.
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DXP & composability: all-in-one or best-of-breed?
The discussion then moved beyond content to the broader digital experience.
Do you see your CMS as one building block in a composable ecosystem? Or rather as part of a larger Digital Experience Platform (DXP)?
Sanity
Sanity deliberately avoids being an all-in-one DXP. It focuses entirely on content. Personalization, marketing automation, and analytics are handled through specialized third-party tools. In a composable architecture, Sanity acts as the content core.
Contentstack
Contentstack doesn’t offer a full suite either, but provides strong integration and personalization capabilities. It positions itself as a central content layer within a broader composable DXP setup.
Optimizely
Optimizely clearly positions itself as a DXP, with built-in personalization, experimentation, DAM, and AI via Opal. Content isn’t just managed and delivered, it’s continuously optimized within one and the same ecosystem.
Sitecore
Sitecore combines CMS, DAM, analytics, personalization, and marketing automation in a broader DXP vision. AI supports the orchestration of the content lifecycle across channels.
The real question isn’t who can do more, but whether you prefer:
One platform that covers a lot
Or a best-of-breed ecosystem you assemble yourself
How AI is changing content structure
An interesting audience question focused on GEO and AEO: content designed not just for people and search engines, but also for AI systems.
Should we model content differently when AI is its reader?
The panel viewed AI as a new channel. Just as content is optimized for SEO, it can also be structured to give language models richer context. Some platforms already offer tooling for this. In other cases, it comes down to implementation choices.
AI also supports content teams by helping with:
Translation
Summarization
Structuring
Quality control
Content governance
That can significantly reduce pressure on editorial teams.
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So… which CMS should you choose?
The panel’s final answer was simple: “It depends...”
That may sound vague, but at least it’s honest. The right CMS depends on your organization’s needs and preferences.
Your choice should consider:
How much freedom you want in your front end stack
Whether your CMS is a pure content repository or part of a DXP
Whether you’re primarily web-focused or truly omnichannel
How much structure your editorial team needs
How much you want to build versus out-of-the-box solutions
And perhaps the most important advice: Don’t make your choice based purely on a demo. Run a hands-on proof of concept. Because the best CMS isn’t the one with the most features. It’s the one that fits your organization, your team, and your digital ambitions.
At iO, we have hands-on experience with all four platforms and regularly support organizations through CMS selection processes, always vendor-neutral.
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