A colour tool that shows its working

What it is

A workspace for constructing palettes from documented colour mathematics, checking whether they hold up, previewing them in realistic contexts, and exporting them into whatever your pipeline needs. It runs in a browser, it is free, and it is supported by advertising that stays out of the way of the work.

What it is not

Colorstruct does not generate colour with AI. There is no model suggesting palettes, no natural-language prompt, and no external generative service anywhere in the colour engine. Every colour it produces comes from a specific, inspectable calculation in OKLCH: a hue angle, a lightness ramp, a chroma ramp, a gamut mapping strategy. Where variation is offered it is seeded, so the same seed rebuilds the same palette exactly.

This is a design decision, not a limitation. A palette you cannot explain is a palette you cannot defend in a review, extend six months later, or hand to an engineer with confidence.

Accessibility is a feature, not a checkbox

The accessibility inspector is a permanent panel, not a validation step at the end. It reports pairwise contrast for every combination, results for normal text, large text and non-text use, colour-vision simulations, and calculated adjustments that reach a given threshold with the smallest change.

It never edits your palette. Your palette does not have to be accessible — plenty of legitimate work is not — but you should always know what it does, and the interface explaining that must itself be usable by everyone.

Anonymous by default

Building, editing, importing, extracting from an image, checking contrast, previewing and every export format work without an account. Work stays in your browser’s local storage until you deliberately save or publish it. An account is only needed to keep things permanently, publish them, follow people, like, or make collections.

How it is built

The colour engine is a standalone, documented TypeScript module with no dependency on the interface, covered by unit tests for conversions, harmony angles, hue wrapping, gamut handling, contrast and the edge cases around black, white and zero chroma.