OpenAI leads with #000000 (black) set in OpenAI Sans; Anthropic with #D97757 (vermilion) set in Anthropic Sans. Controls are pill-shaped versus 8px, and 6 of 7 versus 7 of 9 key color pairings pass WCAG 2.1 AA.
Body copy at reading size.
Body copy at reading size.
Measured values side by side. The last column is arithmetic on those values, not a judgment.
| Attribute | OpenAI | Anthropic | Difference |
|---|---|---|---|
| Primary color | #000000 · Black | #D97757 · Vermilion | Different hue, OKLab ΔE 68.5 |
| Text color | #0D0D0D | #141413 | OKLab ΔE 3.2 |
| Canvas | #FFFFFF · Neutral white | #FAF9F5 · Warm paper | Different surface tone |
| Mode | Light | Light | Same |
| Heading font | OpenAI Sans (free stand-in Inter) | Anthropic Sans (free stand-in Inter) | Same free stand-in (Inter) |
| Body font | OpenAI Sans (free stand-in Inter) | Anthropic Serif (free stand-in Source Serif 4) | Different families |
| Control radius | pill (9999px) | 8px | OpenAI uses pill controls |
| Card radius | 24px | 16px | OpenAI rounder by 8px |
| Radius style | Pill | Rounded | Different |
| WCAG 2.1 AA | 6 of 7 (86%) | 7 of 9 (78%) | OpenAI higher by 8 pts |
| WCAG 2.1 AAA | 5 of 7 (71%) | 4 of 9 (44%) | OpenAI higher by 27 pts |
| Button label contrast | 21.00:1 | 6.04:1 | OpenAI higher by 14.96 |
| Technical SEO | Not published (HTTP 403) | 97/100 | Not comparable |
| Data from | 10 Nov 2026 | 10 Nov 2026 | Both reference snapshots |
| Pairing | OpenAI | Anthropic |
|---|---|---|
| Body text on surface | Aa19.44:1AA | Aa17.50:1AA |
| Secondary text on surface | Aa6.58:1AA | Aa6.26:1AA |
| Primary as link/text on surface | Aa21.00:1AA | Aa2.96:1Fail |
| Button label on primary | Aa21.00:1AA | Aa6.04:1AA |
| Accent on surface | Aa3.20:1Large | Aa2.78:1Fail |
| White on secondary | Aa19.44:1AA | Aa18.43:1AA |
| Dark mode: text on canvas | Aa18.17:1AA | Aa17.64:1AA |
| Body text on white | same colors as another pairing | Aa18.43:1AA |
| Dark mode: primary on canvas | same colors as another pairing | Aa6.15:1AA |
Homepage checks from each dated scan. Sites that refuse automated requests show no score rather than an estimate.
openai.com refuses automated requests (HTTP 403), so no SEO metrics are published for it. Nothing is estimated.
OpenAI uses #000000 as primary, #0D0D0D as secondary and #10A37F as accent, with #0D0D0D text on #FFFFFF. Anthropic uses #D97757 as primary, #141413 as secondary and #6A9BCC as accent, with #141413 text on #FAF9F5. Click any swatch on this page to copy its hex code.
OpenAI sets headings in OpenAI Sans (free stand-in Inter). Anthropic sets headings in Anthropic Sans (free stand-in Inter) and body text in Anthropic Serif (free stand-in Source Serif 4). Proprietary faces are previewed with the named free Google Fonts stand-in.
OpenAI uses pill-shaped controls and 24px cards (pill geometry). Anthropic uses 8px controls and 16px cards (rounded geometry). Control radius: openai uses pill controls.
OpenAI passes 6 of 7 key pairings at WCAG 2.1 AA (86%) and 5 at AAA. Anthropic passes 7 of 9 at AA (78%) and 4 at AAA. The pairings cover body text, links, buttons and dark mode.
openai.com refuses automated requests (HTTP 403), so no SEO score is published for it. Anthropic's homepage scores 97/100, with 13 of 14 checks passing. Scores come from SuiteAnvil's 14 weighted technical checks (title, description, H1, canonical, Open Graph, structured data, sitemap, HTTPS and more) and are never estimated.
Enter your URL in the benchmark form on this page. SuiteAnvil scans your homepage, CSS and sitemap, then opens the same side-by-side view of your site against Anthropic, or against OpenAI.
Dated snapshots of each company's public website styling for educational and interoperability purposes. Brands evolve; values may change. Names and logos are trademarks of their owners, shown for identification only; SuiteAnvil is not affiliated with or endorsed by OpenAI or Anthropic.
SuiteAnvil extracts publicly visible design tokens, logos, and font references for workflow automation. You are responsible for ensuring you hold valid commercial rights or client authorization for any proprietary fonts, trademarks, and brand assets before commercial publication. Licensing notice