Accessibility

Ensuring that apps are accessible to a broad range of users is an essential part of building a high-quality app. Applications that are poorly designed create barriers to people of all ages. The UN Convention on the Rights of Persons with Disabilities states the moral and legal imperative to ensure universal access to information systems; countries around the world enforce accessibility as a requirement; and companies recognize the business advantages of maximizing access to their services.

We strongly encourage you to include an accessibility checklist as a key criteria before shipping your app. Flutter is committed to supporting developers in making their apps more accessible, and includes first-class framework support for accessibility in addition to that provided by the underlying operating system, including:

UI Design and styling

Assistive Technologies (Screen Reader) supports

Accessibility standards and regulations help ensure that products are accessible to people with disabilities. Many of these have been enacted into laws and policies, making them requirements for products and services.

• WCAG 2: Web Content Accessibility Guidelines (WCAG) 2 is an internationally recognized standard for making web content more accessible to people with disabilities. It is a stable, technical standard developed by the World Wide Web Consortium (W3C).

• EN 301 549: EN 301 549 is the European harmonized standard for accessibility requirements for Information and Communication Technology (ICT) products and services.

• VPAT: The Voluntary Product Accessibility Template (VPAT) is a free template that translates accessibility requirements and standards into actionable testing criteria for products and services.

Laws around the world require digital content and services to be accessible to people with disabilities. In the U.S., the Americans with Disabilities Act (ADA) prohibits discrimination in public accommodations. Section 508 of the Rehabilitation Act requires federal agencies and their contractors to meet WCAG standards for all ICT.

In the EU, the European Accessibility Act (EAA) requires a wide range of public and private sector services to be accessible, primarily using the EN 301 549 as its technical basis.

Ensuring that your app can be used by everyone means building accessibility into it from the start. For some apps, that's easier said than done. In the video below, two of our engineers take a mobile app from a dire accessibility state to one that takes advantage of Flutter's built-in widgets to offer a dramatically more accessible experience.

Here is a non-exhaustive list of things to consider as you prepare your app for release.

• Active interactions. Ensure that all active interactions do something. Any button that can be pushed should do something when pushed. For example, if you have a no-op callback for an onPressed event, change it to show a SnackBar on the screen explaining which control you just pushed.
• Screen reader testing. The screen reader should be able to describe all controls on the page when you tap on them, and the descriptions should be intelligible. Test your app with TalkBack (Android) and VoiceOver (iOS).
• Contrast ratios. We encourage you to have a contrast ratio of at least 4.5:1 between controls or text and the background, with the exception of disabled components. Images should also be vetted for sufficient contrast.
• Context switching. Nothing should change the user's context automatically while typing in information. Generally, the widgets should avoid changing the user's context without some sort of confirmation action.
• Tappable targets. All tappable targets should be at least 48x48 pixels.
• Errors. Important actions should be able to be undone. In fields that show errors, suggest a correction if possible.
• Color vision deficiency testing. Controls should be usable and legible in colorblind and grayscale modes.
• Scale factors. The UI should remain legible and usable at very large scale factors for text size and display scaling.

To learn more about Flutter and accessibility, check out the following articles written by community members:

• A deep dive into Flutter's accessibility widgets
• Semantics in Flutter
• Flutter: Crafting a great experience for screen readers