A11yJSON: The Open Standard Making Physical Accessibility Programmable

How do you tell a navigation app that a building entrance has a fixed ramp but doesn’t allow guide dogs? How do you encode that an elevator has real-time operational status? Until now, the answer has been frustratingly ad-hoc.

The Core Insight

A11yJSON is an open data standard built on GeoJSON (RFC 7946) that provides a structured way to describe physical accessibility information. Created by Sozialhelden e.V.—the Berlin-based nonprofit behind Wheelmap.org, the world’s largest open map of accessible places—it aims to make accessibility data as interoperable as geographic coordinates.

Here’s what valid A11yJSON looks like:

{
  "entrances": [
    { "name": "30th St", "isMainEntrance": true, "isLevel": false },
    { "name": "Side gate", "hasFixedRamp": true }
  ],
  "animalPolicy": {
    "allowsGuideDogs": false
  }
}

Simple. Readable. Standardized. And that simplicity is precisely the point.

Why This Matters

Accessibility data today is a fragmented mess. Every mapping platform, every city database, every venue directory uses different schemas. Want to build an app that helps wheelchair users find accessible restaurants? You’ll need to parse a dozen incompatible data formats—if the data exists at all.

A11yJSON changes this by providing standardized schemas for:

• Physical places (buildings, venues, public spaces)
• Amenities (elevators, escalators, vending machines, sanitary facilities)
• Real-time operational status (is that elevator actually working right now?)
• Policies (dog friendliness, service animal accommodations)
• Media and services (accessible documents, assistive technologies)

The standard is comprehensive yet practical. It covers scenarios from simple venue listings to complex transit station accessibility maps.

Technical Implementation

A11yJSON isn’t just documentation—it’s a fully typed system:

TypeScript support: Import @sozialhelden/a11yjson from npm and get compile-time type checking for your accessibility data structures.

Runtime validation: The underlying SimpleSchema integration provides sophisticated error messages when data doesn’t conform to the specification.

Portable schema: The definition syntax is designed to be readable enough that porting to GraphQL, JSON Schema, or other schema languages is straightforward.

The GeoJSON foundation means accessibility data can be directly integrated with existing mapping infrastructure. No special handling required—it’s just JSON with geographic coordinates and accessibility attributes.

Key Takeaways

• Standards enable ecosystems. Without shared data formats, every accessibility app reinvents the wheel
• GeoJSON foundation is clever. Leveraging an existing RFC means immediate compatibility with mapping tools
• Real-time status matters. Knowing an elevator exists is less useful than knowing it’s currently working
• Policy encoding is underappreciated. Service animal policies, assistance availability, and similar “soft” accessibility factors are now representable
• Open source, open standard. Sozialhelden releases everything publicly, enabling community contribution

Looking Ahead

The potential applications extend far beyond mobility apps:

City planning: Municipalities could publish A11yJSON data for public buildings, enabling accessibility audits and improvement prioritization.

Transit authorities: Real-time elevator/escalator status in A11yJSON format could power accessibility-aware routing in any navigation app.

Review platforms: Yelp, TripAdvisor, and Google Maps could adopt A11yJSON to standardize their accessibility information—and make it exportable.

IoT integration: Elevators and accessible infrastructure could broadcast their status in A11yJSON format, creating a real-time accessibility layer for cities.

The bigger picture: we’re seeing accessibility evolve from an afterthought checkbox to a first-class data concern. When wheelchair accessibility information is as structured and queryable as business hours, when elevator status is as real-time as traffic data, we’ll have built truly inclusive digital infrastructure.

A11yJSON is a small but important step toward that future. It takes the messy, inconsistent world of accessibility data and gives it a schema. And in software, schemas are the foundation of everything that comes next.

Based on: “A11yJSON: A standard to describe the accessibility of the physical world” by Sozialhelden