Color

#3f51ca

#3f51ca
hex#3f51ca
rgbrgb(63, 81, 202)
hslhsl(232, 57%, 52%)
oklchoklch(0.495 0.187 271.3)
Closest name: Denim (#1560bd)Relative luminance 0.1121

Colors that go with #3f51ca

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 →

#cab83f

#3f97ca · #723fca

#ca3f51 · #51ca3f

Split-complementary

Open in tool →

#ca723f · #97ca3f

#ca3f97 · #cab83f · #3fca72

Contrast

#3f51ca as textRatioAAAA largeAAAFix
Aaon white
6.48:1passpassfail
  • AAA: use #374ac8 as the text (7.06:1)
Aaon black
3.24:1failpassfail
  • AA: use #5f6ed3 as the text (4.66:1)
  • AAA: use #8793de as the text (7.26:1)
  • AA: or shift the background to #d9d9d9 (4.59:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #3f51ca as the background.

Brands using this color

Fonts for this mood

#3f51ca reads as cool, modern. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #3f51ca
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 #3f51ca and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/3f51ca-9c9dc4-df864e-231f2d-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