This document is an extension of the licensing agreement.

This brief document defines the minimum integrated features for a tool to be considered either “APCA™ Compliant” or “APCA™ Compatible” and other related issues. This document became necessary due to some unfortunate abuse and improper use of trademarks, code, and importantly in terms of properly presenting the technology. If you have questions, please reach out to info@readtech.org — we’re easy to talk to!

Compatibility Level/Permissible Identification Overview

Conformance Failure Remediation

Unfortunately, due to misuse, tools that are not at least at the APCA minimum level “contrast value”, and that make any claims of being APCA™ or SAPC™, be notified and provided a reasonable period of time to remove the statements or update the implementation.

Regrettably, tools that are improperly implementing the technology and/or that are improperly claiming WCAG 3 compliance, are causing concerns within the W3-AGWG and in the accessibility community at large. Also, there is sufficient misinformation regarding contrast on the internet today, that there is a significant interest in correcting these issues.

As the APCA™ is designed specifically for use in a standard, it is important that tools are unified regarding their application of the technology. As this is a developing standard, it is further important that tool developers follow changes in the APCA™ code or methods, and keep tools updated to prevent discordant results.

Use of Trademarks

The terms “APCA”, “SAPC”, “SACAM”, “Advanced Perceptual Contrast Algorithm”, “Accessible Perceptual Contrast Algorithm”, “APCA™ Contrast”, “APCA™ Compatible”, “APCA™ Compliant”, “APCA™ Certified”, are trademarks of Myndex Research and Andrew Somers, All Rights Reserved, use by limited permission only. Trademarks are not included as part of any open-source license, permission to use only per the limited restrictions listed in this document.

Permission to use revokable at any time for non-compliance per this document or future versions thereof, revocation made in writing to the email address of record of the trademark user.

Regarding WCAG 3.0

The only suitable language at this time is: “APCA™ is the candidate contrast method for WCAG 3, and is currently in public beta. WCAG 3 is still in development and subject to changes prior to adoption.”

Compliance Levels Defined

For the purposes of this document:


All compliance levels require the following:

Use Without Identification

Unidentified use of the APCA algorithm or math is permitted:

APCA™ Contrast Value (no guidelines, no examples)

Use of the term “APCA™ Lc Value” requires at a minimum:

APCA™ Compatible (basic guidelines and basic examples)

Use of the term “APCA™ Compatible” requires at a minimum:

APCA™ Compliant (more complete guidelines and examples)

Use of the term “APCA™ Compliant” requires at a minimum:

Everything as recited in “APCA™ Compatible” above, but further including:

Pending Requirements in development:

APCA™ Certified

For certification, a site or tool must meet the “APCA Compliant” standard above, and then have source code and implementation evaluated and certified by Myndex Research or Accessible Reading Technologies. The certification service will be available at a future date, following the conclusion of the beta period.

Only APCA Certified apps will be permitted to use the trademarked “Powered by APCA” or “APCA™” official logos.

APCA Beta Testers

APCA Beta sites may have different variations on the above requirements, permitted on a case by case basis, under the experimental use case temporary exception.

To become officially involved in the APCA beta program, please send an email to “info@readtech.org” with “APCA Beta” in the subject line.

Further Discussion

We are open for comments, questions, and discussion at the Main APCA Repo Discussions.