Cal Com

The reference for open-source dev-tools brand at peak typographic confidence — Cal Sans 64px H1 on pure white, real booking widget in hero, prestige customer logos.

Developer Tool Open Source Scheduling strong

Design tokens

white

black

darkText

muteGrey

linkBlue

slate41

slate55

lightGrey224

lightGrey211

lightGrey244

shadowOverlay

display: 'Cal Sans UI Variable Light', 'Cal Sans UI Variable Light Placeholder', sans-serif (open-source Cal.com bespoke)
displayAlt: 'Cal Sans', sans-serif (Cal Sans static)
body: Inter, 'Inter Placeholder', sans-serif
bodyAlt: 'Matter Regular', 'Matter Regular Placeholder', sans-serif

Do / Don't

Reference it for

Pure white + pure black extreme monochrome — most disciplined palette in the library
Cal Sans UI Variable Light bespoke font (open-source from cal.com — actually available for download)
64px Cal Sans H1 in pure black on white — three-line wrap
Real product booking widget in hero with Ethan Taylor mock event + duration tabs + Google Meet + timezone + calendar grid
Sign up with Google primary CTA (black pill with Google G icon)
Triple social-proof row: Trustpilot + ProductHunt + Capterra (3 ratings, 5 stars each)
High-prestige YC customer logos: Rho, Deel, Framer, Ramp, PlanetScale, Coinbase
"Cal.com launches v6.5 >" announcement chip above H1 with right-chevron

Do not copy

The Cal Sans UI Variable Light font (technically open-source but distinct to Cal.com brand)
The Cal.com logotype
The Ethan Taylor / Academic Counseling demo event
The customer logos (Rho, Deel, Framer, Ramp, PlanetScale, Coinbase) — Cal.com-specific
The Trustpilot / ProductHunt / Capterra rating numbers — Cal.com-specific
The "Cal.com launches v6.5" version announcement
The Twitter handles (@walker, @kentcdodds, @clementdubost, etc.) — real users

Signature moves

extreme monochrome with a 64px display headline

pure white and pure black at the library's most disciplined, with a 64px Cal-Sans-class H1 wrapping three lines in black on white over an 1224px content rail.

real product widget in the hero

a near-full-fidelity product booking widget sits in the hero (event, duration tabs, timezone, calendar grid), proving the product instead of describing it.

stacked third-party social-proof and prestige logo strip

a triple social-proof row (three review platforms, 5 stars each) plus a prestige customer-logo strip framed by a trust line builds credibility above the fold.

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