# #427bf5

A color — cool, vivid, technical, modern. Deterministic analysis from BrandSweets (no inference).

## Values

- Hex: `#427bf5`
- RGB: rgb(66, 123, 245)
- HSL: hsl(221, 90%, 61%)
- OKLCH: oklch(0.611 0.193 263.1)
- Relative luminance: 0.2192
- Nearest named color: Blue Öyster Cult (#5577ee, Δ 2.079) — https://brandsweets.com/colors/blue-oyster-cult
- Moods: cool, vivid, technical, modern
- Page: https://brandsweets.com/colors/427bf5

## Tints & shades

- Tints (toward white): #5588f6, #6492f7, #77a0f8, #8baef9, #9ebbfa, #adc5fb, #c0d3fc, #d3e0fd, #e2ebfd, #f5f8fe
- Shades (toward black): #2566f4, #0d55f2, #0b4bd5, #0a41b8, #0838a0, #072e83, #052466, #041a49, #031130, #010713

## Harmonies

- Complementary: #f5bc42
- Analogous: #42d4f5, #6342f5
- Triadic: #f5427b, #7bf542
- Split-complementary: #f56342, #d4f542
- Tetradic: #f542d4, #f5bc42, #42f563

## Colors that go with #427bf5

Named partners (harmony on the OKLCH wheel, co-occurrence in curated palettes and brand systems, and the neutrals that carry it), best first:

- **Charcoal** #36454f [role, pool] — Charcoal is the text near-black for #427bf5: softer than #000 and cool enough to feel like part of the same palette. Seen in: Disney (https://brandsweets.com/colors/brands/disney-com), Docker (https://brandsweets.com/colors/brands/docker-com), Zoom (https://brandsweets.com/colors/brands/zoom-us), Hinge (https://brandsweets.com/colors/brands/hinge-co). — https://brandsweets.com/colors/charcoal
- **Crimson** #dc143c [harmony, pool: triadic] — Crimson completes a triad with #427bf5 — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash. Seen in: Behance (https://brandsweets.com/colors/brands/behance-net), WWE (https://brandsweets.com/colors/brands/wwe-com), Foot Locker (https://brandsweets.com/colors/brands/footlocker-com), Pizza Hut (https://brandsweets.com/colors/brands/pizzahut-com). — https://brandsweets.com/colors/crimson
- **Copper** #b87333 [harmony, pool: complementary] — Copper sits directly opposite #427bf5 on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight. Seen in: Notion (https://brandsweets.com/colors/brands/notion). — https://brandsweets.com/colors/copper
- **Amber** #ffbf00 [pool] — Amber is paired with #427bf5 in 11 real palettes, including Google's brand system and Heatwave, as the accent. Seen in: Google (https://brandsweets.com/colors/brands/google-com), Heatwave (https://brandsweets.com/palettes/warm#heatwave), Walmart (https://brandsweets.com/colors/brands/walmart-com), Mastodon hosted on mastodon.social (https://brandsweets.com/colors/brands/mastodon-social). — https://brandsweets.com/colors/amber
- **Blue** #0000ff [pool] — 13 real palettes, including Penpot's brand system and Cargo's brand system put Blue beside #427bf5, as the supporting colour. Seen in: Penpot (https://brandsweets.com/colors/brands/penpot-app), Cargo (https://brandsweets.com/colors/brands/cargo-site), Samsung (https://brandsweets.com/colors/brands/samsung-com), Readymag (https://brandsweets.com/colors/brands/readymag-com). — https://brandsweets.com/colors/blue
- **Cobalt Blue** #0047ab [pool] — Designers have shipped Cobalt Blue with #427bf5: 11 real palettes, including Carrefour's brand system and Behance's brand system, as the accent. Seen in: Carrefour (https://brandsweets.com/colors/brands/carrefour-com), Behance (https://brandsweets.com/colors/brands/behance-net), Nokia (https://brandsweets.com/colors/brands/nokia-com), Nivea (https://brandsweets.com/colors/brands/nivea-com). — https://brandsweets.com/colors/cobalt
- **Deep Sky Blue** #00bfff [pool] — Designers have shipped Deep Sky Blue with #427bf5: 9 real palettes, including Patreon's brand system and Venmo's brand system, as the supporting colour. Seen in: Patreon (https://brandsweets.com/colors/brands/patreon-com), Venmo (https://brandsweets.com/colors/brands/venmo-com), Elastic (https://brandsweets.com/colors/brands/elastic-co), Calm (https://brandsweets.com/colors/brands/calm-com). — https://brandsweets.com/colors/deepskyblue
- **Denim** #1560bd [pool] — Designers have shipped Denim with #427bf5: 18 real palettes, including Coursera's brand system and Guinness's brand system, as the accent. Seen in: Coursera (https://brandsweets.com/colors/brands/coursera-org), Guinness (https://brandsweets.com/colors/brands/guinness-com), Fivetran blue (https://brandsweets.com/colors/brands/fivetran-com), Venmo (https://brandsweets.com/colors/brands/venmo-com). — https://brandsweets.com/colors/denim

## Contrast (WCAG 2.x, as text)

- On white (#ffffff): 3.9:1 — AA fail, AA-large pass, AAA fail. Fix: AA: text → #2f6df4 (4.55:1); AA: background → #171717 (4.6:1); AAA: text → #0b4bd5 (7.04:1)
- On black (#000000): 5.38:1 — AA pass, AA-large pass, AAA fail. Fix: AAA: text → #6996f7 (7.31:1)

## Brands using this color

- **PostHog** — secondary #2f80fa (Δ 1.695) — https://brandsweets.com/colors/brands/posthog-com
- **Spline** — primary #4482fc (Δ 2) — https://brandsweets.com/colors/brands/spline-design

## Curated palettes containing it

- **Playground** (bold, playful, warm) — #ff8c00, #3b82f6, #22c55e, #fff8e7, #1d1d1d — Orange, blue and green — the colors of playground equipment; loud, cheerful, obviously for kids. — tool: https://brandsweets.com/palettes/new/ff8c00-3b82f6-22c55e-fff8e7-1d1d1d — collection: https://brandsweets.com/palettes/bold

## Fonts for this mood

- technical: https://brandsweets.com/fonts/mood/technical
- modern: https://brandsweets.com/fonts/mood/modern

## Palette tool

Open this color locked as the lead with four explored companions: https://brandsweets.com/palettes/new/427bf5-9ca4c4-df6b4e-211f2d-e9eff1?lock=0&style=vibrant
(Humans lock/regenerate in the tool; the URL is the state — read `lock=` back to see what they kept.)

## Connect an agent

Point any MCP client at the BrandSweets colors endpoint for the same engine:

- Endpoint: https://mcp.brandsweets.com/colors/mcp
- Tools: `analyze_color` (e.g. `analyze_color({ color: "#427bf5" })`), `check_contrast` (with fixes), `generate_palette` (explore around locks), `suggest_palette` (mood/industry → curated-first), `list_palettes`.