#3f91cf as text	Ratio	AA	AA large	AAA	Fix
Aaon white	3.41:1	fail	pass	fail	AA: use #2d79b4 as the text (4.66:1) AAA: use #225b87 as the text (7.21:1) AA: or shift the background to #242424 (4.56:1)
Aaon black	6.16:1	pass	pass	fail	AAA: use #549cd4 as the text (7.08:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #3f91cf as the background.

Brands using this color

Retoolaccent · #518dd2 · Δ1.859

Fonts for this mood

#3f91cf reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

Technical fonts →Modern fonts →

mcpConnect your agent — build around #3f91cf

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 #3f91cf and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/3f91cf-9caec4-df4e56-1f212d-e9f1f1?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