ATAG

ATAG — Authoring Tool Accessibility Guidelines — is the W3C standard for tools that create web content. Where WCAG addresses what published content must do for end users, ATAG addresses what authoring tools must do for the people creating that content.

Two parts, two audiences

ATAG 2.0 splits into:

• Part A — Make the authoring tool user interface accessible. The tool itself must be usable by content creators with disabilities. A blind editor must be able to use the CMS that produces your articles; a low-vision designer must be able to operate the design plugin that exports your icons.
• Part B — Support the production of accessible content. The tool must help authors produce accessible output. A CMS that lets authors insert images without prompting for alt text is ATAG Part-B non-compliant, even if its UI is perfectly accessible.

Why Part B is harder

Part A is essentially “apply WCAG to your own product.” That’s a known problem with known patterns. Part B is more demanding because it requires the tool to know what accessible output looks like and nudge or constrain the author towards it.

Operational examples of Part B done well:

• A CMS image-upload dialog that requires alt text, with an explicit “mark this image as decorative” checkbox so authors don’t ship empty alt to escape the prompt.
• A markdown editor that warns when a heading level is skipped (h1 → h3 without h2).
• A design tool that surfaces contrast-ratio violations in real time as the author picks colours.

What ATAG is not

ATAG is not a procurement requirement in most jurisdictions. EU Web Accessibility Directive and EAA cite EN 301 549, which references WCAG (not ATAG). US Section 508 is similar. Buyers occasionally ask vendors to demonstrate ATAG conformance for in-house CMS work, but standardised ATAG VPATs are rare.

Why it still matters

The most accessible site in the world becomes inaccessible the moment authors can’t produce accessible content in it. A CMS with poor ATAG conformance is a multiplier on accessibility debt: every new article, every new image, every new form widget arrives with the same predictable omissions. ATAG-aware tools shift the entry cost of accessibility to near-zero per author.

This is the lens to apply when evaluating CMS platforms, design tools, no-code builders, and AI-assisted authoring: not “is the tool itself accessible?” but “does the tool make accessibility easy for the people publishing through it?”