Indigo SaaS
Open in tool →The dependable indigo-and-emerald B2B pairing: indigo for primary actions, emerald reserved for success states.
Color
#21b581
#21b581
hex
#21b581rgb
rgb(33, 181, 129)hsl
hsl(159, 69%, 42%)oklch
oklch(0.687 0.141 163)Closest name: mediumseagreen (#3cb371)Relative luminance 0.3496
Colors that go with #21b581
Charcoal, Hot Pink and Blue lead the list. Each partner is a real named colour with the reason it works — a wheel relationship, a neutral that carries it, or a pairing lifted from a palette or brand system that actually shipped — and every pair opens in the palette tool.
Charcoal #36454f
neutralshippedCharcoal is the text near-black for #21b581: softer than #000 and cool enough to feel like part of the same palette.
Hot Pink #ff69b4
complementaryshippedHot Pink sits directly opposite #21b581 on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Blue #0000ff
shipped4 real palettes, including Unity's brand system and Spotify's brand system put Blue beside #21b581, as the supporting colour.
Cornflower Blue #6495ed
triadicshippedCornflower Blue completes a triad with #21b581 — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash.
Midnight Blue #191970
shipped4 real palettes, including Fintech Trust and Telehealth put Midnight Blue beside #21b581, as the text colour against it.
Mustard Yellow #ffdb58
shipped5 real palettes, including Diner and Meadow put Mustard Yellow beside #21b581, as the accent.
Royal Blue #4169e1
shippedRoyal Blue is paired with #21b581 in 5 real palettes, including Khan Academy's brand system and Brilliant's brand system, as the accent.
Taupe #483c32
shippedTaupe is paired with #21b581 in 15 real palettes, including Chime's brand system and Undergrowth, as the lead colour.
Real palettes that use #21b581
Tints & shades
Harmonies
Contrast
| #21b581 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 2.63:1 | fail | fail | fail | |
Aaon black | 7.99:1 | pass | pass | pass | Passes AAA — no fix needed. |
Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #21b581 as the background.
Brands using this color
No public brand in the corpus uses this exact color yet. Extract a brand to add one.
Palettes built around it
mcpConnect your agent — build around #21b581
live endpointPoint any MCP client at the shared colors endpoint and your agent gets the same engine as this page — direct_palette, edit_direction, check_palette, check_contrast — read-only, no key. Every direction it proposes comes with a /colors/d/… link: open it, lock what you like, paste the link back, and the agent edits rather than re-rolls.
endpoint
https://mcp.brandsweets.com/colors/mcpclaude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
try this prompt
›analyze #21b581 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/21b581-a2beb8-d459c0-1f2c2d-e9f1eb?lock=0&style=vibrantWant the agent to remember your picks and write them into a living brand? Create a free BrandSweets workspace.
Machine-readable: color.md