APCA Contrast

By Jared Lyvers, ldnddev — March 2, 2026

Accessibility testing got a lot more useful in dd_wcag. If you've used the app before, you already know it handles color input cleanly (HEX, RGB/RGBA, HSL), converts values in real time, and gives you WCAG contrast checks tied to text size and weight. That foundation is still here. The major update is that dd_wcag now checks APCA contrast alongside WCAG.

Why APCA Matters

That matters because WCAG ratio alone can miss how contrast actually feels on modern displays, especially for smaller text. APCA adds a more perceptual approach by scoring readability with an Lc value, so you can make decisions that better match real user experience, not just pass/fail math.

What This Means Day-to-Day

• You can compare WCAG and APCA results side by side in the Contrast tab.
• You can quickly test how font size and bold weight change APCA pass/fail outcomes.
• You can open browser preview (Ctrl+O) and validate the same content with real CSS pixel sizing, while seeing both WCAG and APCA info.

Built for Real Projects

This update is practical for teams building in Drupal, WordPress, and custom stacks because accessibility bugs often show up in content-heavy interfaces: cards, banners, body copy, and component variants that change by theme or editor settings. APCA helps catch readability risks earlier, before design QA or production audits.

Using Both Standards

A quick note on tradeoffs: WCAG is still essential for compliance workflows, and APCA is essential for perceptual accuracy. Using both gives you stronger coverage and fewer surprises.

If your team wants a faster accessibility feedback loop while designing and building, this update makes dd_wcag a stronger daily utility, not just a one-time checker.

Get It

The project is MIT licensed, and ready for daily use.

What unexpected tool combinations have you discovered? I've found that the best workflows come from repurposing tools beyond their original design. Reply and share your favorites.

dd_wcag is available at https://bitbucket.org/ldnddev/dd_wcag — pulls, forks, and feedback welcome.

Run
cargo run
Build Binary
cargo build --release
./target/release/dd_wcag
The app loads theme from: - ~/.config/ldnddev/dd_wcag/theme.yml

Install Script
Install from current checkout:

./install.sh

Until next time, Jared Lyvers