Circuit
Open in tool →Violet plus cyan is the current AI-product signal — pair it with pure black type to keep it from going candy.
Color
#21b3ca
#21b3ca
hex
#21b3cargb
rgb(33, 179, 202)hsl
hsl(188, 72%, 46%)oklch
oklch(0.706 0.117 211.6)Closest name: Aquarius (#2db0ce)Relative luminance 0.3683
Colors that go with #21b3ca
Charcoal, Tomato and Denim 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 #21b3ca: softer than #000 and cool enough to feel like part of the same palette.
Tomato #ff6347
complementaryshippedTomato sits directly opposite #21b3ca on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Denim #1560bd
shippedDesigners have shipped Denim with #21b3ca: 7 real palettes, including Coca-Cola's brand system and Venmo's brand system, as the accent.
Dodger Blue #1e90ff
shippedDesigners have shipped Dodger Blue with #21b3ca: 5 real palettes, including Figma's brand system and Patreon's brand system, as the accent.
Midnight Blue #191970
shipped9 real palettes, including Confluent's brand system and Ford's brand system put Midnight Blue beside #21b3ca, as the lead colour.
Orange #ffa500
shipped4 real palettes, including Mistral AI's brand system and Gopro's brand system put Orange beside #21b3ca, as the supporting colour.
Royal Blue #4169e1
shippedRoyal Blue is paired with #21b3ca in 7 real palettes, including Confluent's brand system and Elastic's brand system, as the supporting colour.
Sky Blue #87ceeb
shippedSky Blue is paired with #21b3ca in 4 real palettes, including Max's brand system and Coastal, as the lead colour.
Real palettes that use #21b3ca
Tints & shades
Harmonies
Contrast
| #21b3ca as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 2.51:1 | fail | fail | fail | |
Aaon black | 8.37:1 | 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 #21b3ca as the background.
Brands using this color
Palettes built around it
Fonts for this mood
#21b3ca reads as cool, vivid, technical. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #21b3ca
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 #21b3ca and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/21b3ca-a2b7be-df4e81-1f252d-e9f1ee?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