Color Name Finder

Give it a colour — hex, RGB or the picker — and it returns the eight closest named colours from three different vocabularies: the CSS named colours you can write directly in a stylesheet, the default Tailwind palette from slate-50 through rose-700, and the names from the XKCD colour survey, which asked a couple of hundred thousand people what they would call a swatch and kept the answers that agreed.

Distance is measured in OKLab rather than by comparing RGB values, and that choice is what makes the ranking usable. RGB is a storage format, not a model of vision: the straight-line distance from black to pure blue and from black to pure green is 255 in both cases, yet green is close to twice as bright to the eye. In OKLab those two land at lightness 0.45 and 0.87, which is what you actually see. A nearest-colour search in RGB will happily tell you that a dark saturated blue is the closest match to something that reads as nothing like it, because the arithmetic gave equal weight to a channel the eye barely notices and one it is exquisitely sensitive to.

The three vocabularies are useful for different reasons rather than being three attempts at the same list. The CSS names are the only ones you can type into a stylesheet and have work, and they are a historical accident — inherited from X11, full of duplicates like gray and grey and oddities like rebeccapurple, added in 2014 as a memorial. Tailwind's names tell you which token to reach for in a project already using it. The survey names are the ones ordinary speakers actually use, which is why they include things no standards body would ratify and why they are the right list when you are trying to describe a colour to a person rather than a compiler.

What a nearest name does not give you is a substitute. The closest CSS colour to a brand hex is closest, not equal, and swapping it in shifts the colour by however far the match was — fine for a sketch or a conversation, not for the logo.