What font does Anthropic use?
Anthropic’s site pairs a serif headline with a sans serif interface, the same combination as in the Claude app. All three families are variable fonts, served from the Webflow asset CDN the site is built on.
Short answer: Anthropic’s website uses its own type family: Anthropic Sans for most text, Anthropic Serif for headlines and reading passages, and Anthropic Mono for small technical details.
Anthropic Sans
Self-hosted76.7%- CSS name
Anthropic Sans- Weights
- 400, 500, 600, 700
- Sizes
- 60.9px · 24px · 16px · 15px · 12px
- Served from
- cdn.prod.website-files.com
Anthropic Serif
Self-hosted21.1%- CSS name
Anthropic Serif- Weights
- 400, 500, 600
- Sizes
- 68.3px · 24px · 20px · 18px
- Served from
- cdn.prod.website-files.com
Anthropic Mono
Self-hosted2.2%- CSS name
Anthropic Mono- Weights
- 400
- Sizes
- 16px
- Served from
- cdn.prod.website-files.com
Sizes, weights and spacing by role
These are computed values from the live page, which is what the Font Inspector panel shows when you click each element.
| Role | Font | Size | Weight | Line height | Letter spacing |
|---|---|---|---|---|---|
| Headline | Anthropic Serif | 68.3px | 500 | 1.1 | normal |
| Subheading | Anthropic Sans | 24px | 600 | 1.3 | normal |
| Body text | Anthropic Serif | 18px | 400 | 1.4 | normal |
The main font stack in the CSS:
font-family: "Anthropic Sans", Arial, sans-serif;- The headline size of 68.3px is not a round number, which points to fluid type: the size is calculated from the window width.
- No letter spacing adjustments are applied, even on the large serif headline.
- The font files are served from Webflow’s asset CDN, which tells you the marketing site is built with Webflow.
Check any site yourself in one click.
Sites change their type without notice. Font Inspector shows the rendered font, size, weight and spacing of any text on anthropic.com or anywhere else, and lists every font on the page. Free, no account.
About the fonts, and whether you can use them
Anthropic Sans
Anthropic’s own sans serif, a variable font covering weights 300 to 800. It carries navigation, subheadings and most body text.
Can you use it? It is a proprietary brand typeface and is not available to license. Source Sans 3 and Figtree are free alternatives with a similar friendly, readable character.
On Google Fonts: Source Sans 3, Figtree.
Anthropic Serif
The serif member of the family, used for the main headline and for longer introductory text.
Can you use it? Also proprietary. Newsreader and Source Serif 4 are free serifs that work for both headlines and paragraphs.
On Google Fonts: Newsreader, Source Serif 4.
Anthropic Mono
The monospaced member of the family, used sparingly for labels.
Can you use it? Proprietary. JetBrains Mono, which the site also declares, is free and open source.
On Google Fonts: JetBrains Mono, IBM Plex Mono.
Finding a font does not license it. More in how to get a font you found, legally.
Get a similar look with a free font
This starter uses Source Sans 3, which is open source, with the sizes and spacing measured above. It is an approximation, not a copy of Anthropic’s brand typeface.
/* Approximates the Anthropic look with a free font */
body {
font-family: "Source Sans 3", system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
}
h1 {
font-size: 4.26875rem; /* 68.3px */
font-weight: 500;
line-height: 1.1;
}
p {
font-size: 1.125rem; /* 18px */
font-weight: 400;
line-height: 1.4;
}How we checked
We opened anthropic.com in Chrome on September 20, 2026 and read the computed styles of its visible text: the declared font stack, the font actually rendered, and how much of the page’s text each family sets. That is the same data the Font Inspector extension shows under Fonts on this page. We re-check these pages periodically, and the date above shows the last inspection.
Anthropic and its typefaces are trademarks of their respective owners. Font Inspector is not affiliated with Anthropic.
Questions & answers
What font does Anthropic use on its website?+
Anthropic’s website uses its own type family: Anthropic Sans for most text, Anthropic Serif for headlines and reading passages, and Anthropic Mono for small technical details.
Can I use the Anthropic font?+
It is a proprietary brand typeface and is not available to license. Source Sans 3 and Figtree are free alternatives with a similar friendly, readable character.
What is a free font similar to Anthropic Sans?+
Source Sans 3 and Figtree are free on Google Fonts and give a similar feel. No free font is an exact match, so compare it with your own text first.
How can I check what font Anthropic uses myself?+
Open anthropic.com, then click any text with the Font Inspector extension, or right-click, choose Inspect and look at Rendered Fonts in the Computed tab. Sites change their typography, so checking the live page is the only way to be sure.