Color

#5b57cb

#5b57cb
hex#5b57cb
rgbrgb(91, 87, 203)
hslhsl(242, 53%, 57%)
oklchoklch(0.525 0.175 280.1)
Closest name: slateblue (#6a5acd)Relative luminance 0.1335

Colors that go with #5b57cb

Charcoal, Sea Green and Amber 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.

Tints & shades

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

Harmonies

Complementary

Open in tool →

#c8cb57

#578dcb · #9557cb

#cb5b57 · #57cb5b

Split-complementary

Open in tool →

#cb9557 · #8dcb57

#cb578d · #c8cb57 · #57cb95

Contrast

#5b57cb as textRatioAAAA largeAAAFix
Aaon white
5.72:1passpassfail
  • AAA: use #4844c5 as the text (7.22:1)
Aaon black
3.67:1failpassfail
  • AA: use #6e6bd1 as the text (4.69:1)
  • AAA: use #908edc as the text (7.09:1)
  • AA: or shift the background to #e6e6e6 (4.58:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #5b57cb 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

#5b57cb reads as cool, modern. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #5b57cb
live endpoint

Point 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.

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

analyze #5b57cb and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/5b57cb-a29cc4-df9e4e-261f2d-e9edf1?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