Sample any pixel in an image, get hex / RGB / HSL, and pull a full palette in one click.
Every visual artefact you ship has a tool behind it. The tabs that do not need a design system: a drop-resize-compress loop before a hero lands, a QR for a poster, a swatch you picked off a screenshot. All of those happen in your browser, so the artefacts never leave the machine you are sitting at.
HEX for a flat, opaque brand value, because it is the most portable and the least surprising. Use RGB when the value has to carry alpha, and HSL when the system derives tints and shades, since lightness is comprehensible to whoever maintains the theme next.
Colour management. A design tool may render in a wider working space while the browser assumes sRGB, and a value pasted as HEX is interpreted in whichever space the receiving app has active. Compare the swatch inside a browser, not only between two design tools.
Read the ratio rather than trusting your eye: the WCAG thresholds are about 4.5:1 for body text and 3:1 for large text and interface edges. Pick the pair here, then verify the ratio - and remember that a colour which passes on a white card can fail once it sits on a tinted panel.