This repository is the codebase for ContrastGrid.com.

This online tool takes one or more lists of names/colors (in most common formats) and generates a grid matrix showing the colors’ contrast ratio against each other. If entering a name for the color, separate it with a colon (:).

This is useful when evaluating color systems, and which colors can be paired together while still remaining accessible (per WCAG 2.1 1.4.3 Minimum Contrast Success Criterion).

I had a lot of fun adding some really cool features into this:

• Extremely lightweight. Built with vanilla JavaScript and CSS.
• Saves the input colors to the URL, so the link can be shared or bookmarked (and ability to use back/forward to navigate).
• Ability to ingest lots of color formats such as hex, HSL, etc. We use the TinyColor library, which accepts formats such as hex, HSL, named, HSV, etc. See here for more info.
• Ability to specify different sets of colors on the X and Y axes (and flip them if you want).
• Easy copy/pasting of CSS with variable names (even with comments afterwards). The following code will parse perfectly:

--teen-party--primary: #cc208e; /* accessibile on white, not on dark */
--teen-party--secondary: #6713d2; /* accessibile on white, not on dark */
--cotton-candy--primary: #00dbde; /* not accessibile on white. Accessible on dark */
--cotton-candy--secondary: #fc00ff; /* not accessibile on white. 3.19:1 on dark */

• Easy copying and pasting from Sass maps into the form. The following will work perfectly (the invalid lines will be discarded):

$palette: (
  blue-40: #185d87,
  blue-45: #0068a8,
  blue-50: #177ab6,
  blue-55: #2284c0,
  blue-60: #37a9ef,
  blue-70: #89d2ff,
  blue-90: #cdebf9,
);

• Table headings (both column and row) will become “sticky” and stay in the viewport. This is useful when evaluating very large color systems which requires both horizontal and vertical scrolling.
• Super nifty "flip axis data" button (↑↓) that will flip the values in the X and Y coordinates.

The concept of this site is inspired by Eightshapes' Contrast Grid, as well as Kate Deibel's Contrast Table Analyzer. Both of these tools are excellent, but didn’t provide exactly what I was looking for.