Headless CMS Accessibility: Sanity, Strapi & Contentful Content Guardrails

Developers can write 100% accessible frontend code, but if marketing teams and blog editors upload images without alt text, skip heading levels, or create unlabelled tables inside a Headless CMS (like Sanity, Strapi, Contentful, or Payload), the live website instantly falls out of compliance. Building Schema-Level Guardrails prevents editors from publishing inaccessible content.

The Content Authoring Accessibility Dilemma

Content authors are typically writers and marketers without formal accessibility training. Relying on editorial guidelines alone leads to human error. Enforcing validation rules directly inside the CMS editorial interface guarantees baseline compliance before publishing.

Schema-Level Validation: Mandatory Alt Text & Captions

Configure your image schemas so publishing is rejected if the author fails to provide alternative text or explicitly designate the image as decorative:

// Sanity Schema Definition (schemaTypes/accessibleImage.js)
export default {
  name: 'accessibleImage',
  type: 'image',
  title: 'Accessible Image',
  fields: [
    {
      name: 'alt',
      type: 'string',
      title: 'Alternative Text (Alt)',
      description: 'Describe the image for blind and visually impaired users. Leave empty only if decorative.',
      validation: (Rule) => Rule.custom((alt, context) => {
        const isDecorative = context.parent?.isDecorative;
        if (!isDecorative && (!alt || alt.trim().length === 0)) {
          return 'Alternative text is mandatory unless marked as decorative.';
        }
        return true;
      }),
    },
    {
      name: 'isDecorative',
      type: 'boolean',
      title: 'Decorative Image',
      description: 'Check if this image is purely decorative and contains no informative text.',
    }
  ]
}

Enforcing Semantic Heading Hierarchies

Configure the rich text editor (Portable Text, Markdown, or Slate) to restrict heading choices. For example, ban `<h1>` inside the body editor (since the page title already uses `<h1>`), ensuring authors only use `<h2>`, `<h3>`, and `<h4>` in proper sequence.

Guardrails for Accessible Table and Media Embeds

Require table blocks to designate whether the first row or first column serves as table headers (`<th scope="col">`), preventing unsemantic layout grids.