Color

#666fe5

#666fe5
hex#666fe5
rgbrgb(102, 111, 229)
hslhsl(236, 71%, 65%)
oklchoklch(0.595 0.176 276.4)
Closest name: Blue Öyster Cult (#5577ee)Relative luminance 0.1985

Tints & shades

Every swatch is its own page — click any to analyze it.

Harmonies

Complementary

Open in tool →

#e5dd66

#66aee5 · #9d66e5

#e5666f · #6fe566

Split-complementary

Open in tool →

#e59d66 · #aee566

#e566ae · #e5dd66 · #66e59d

Contrast

#666fe5 as textRatioAAAA largeAAAFix
Aaon white
4.23:1failpassfail
  • AA: use #5e67e4 as the text (4.63:1)
  • AAA: use #3642dd as the text (7.05:1)
  • AA: or shift the background to #0f0f0f (4.54:1)
Aaon black
4.97:1passpassfail
  • AAA: use #8990eb as the text (7.25:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #666fe5 as the background.

Brands using this color

No public brand in the corpus uses this exact color yet. Extract a brand to add one.

Fonts for this mood

#666fe5 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #666fe5
live endpoint

Point any MCP client at the shared colors endpoint and your agent gets the same engine as this page — generate_palette, check_contrast, analyze_color — read-only, no key. Every palette it proposes comes with a /palettes/new/… link: open it, lock what you like, paste the link back.

endpointhttps://mcp.brandsweets.com/colors/mcp
claude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
try this prompt

analyze #666fe5 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/666fe5-9e9cc4-df8f4e-241f2d-e9eef1?lock=0&style=vibrant

Want the agent to remember your picks and write them into a living brand? Create a free BrandSweets workspace.

Machine-readable: color.md