Extract a Website's Design System

Context.dev’s Styleguide API returns a website’s full styleguide:

mode: light or dark
colors: accent, background, text (hex)
typography: detected headings (h1–h4) and p with fontFamily, fontFallbacks, fontSize, fontWeight, lineHeight, letterSpacing
elementSpacing: xs, sm, md, lg, xl
shadows: sm, md, lg, xl, inner
components: detected button variants (primary, secondary, link) and card with full computed CSS
fontLinks: Google or @font-face font files keyed by family, with downloadable URLs per weight

A separate fonts-only endpoint returns the typography subset for a fraction of the cost.

Integrate Context.dev's Design System API in your app

Open in Cursor

Prerequisites

A Context.dev API key. Sign up at context.dev/signup, copy the key from the dashboard (prefix ctxt_secret_), and export it:
```
export CONTEXT_DEV_API_KEY="ctxt_secret_..."
```
An SDK (optional). Install for your language, or skip the install and call directly with curl:
npm install context.dev

Extract the full styleguide

GET /web/styleguide takes in a domain (or a webpage URL) and returns the website’s full design system.

curl -G https://api.context.dev/v1/web/styleguide \
  -H "Authorization: Bearer $CONTEXT_DEV_API_KEY" \
  --data-urlencode "domain=vercel.com"

10 credits per successful call

Request Parameters

Either domain or directUrl must be provided, but not both.

Parameter	Type	Description
`domain`	string	Domain to extract the styleguide from (e.g. `vercel.com`).
`directUrl`	string	A specific URL to fetch the styleguide from directly, bypassing domain resolution (e.g. `https://stripe.com/pricing`).
`maxAgeMs`	integer	Max cache age before a hard refresh. Defaults to `7776000000` (90 days). Clamped to `[86400000, 31536000000]` (1 day – 1 year).
`timeoutMS`	integer (1000–300000)	Abort with a 408 if the request exceeds this many milliseconds. Max `300000` (5 min).

Response

{
  "status": "ok",
  "domain": "vercel.com",
  "code": 200,
  "styleguide": {
    "mode": "light",
    "colors": {
      "accent": "#000000",
      "background": "#fafafa",
      "text": "#171717"
    },
    "typography": {
      "headings": {
        "h1": {
          "fontFamily": "Geist",
          "fontFallbacks": ["Geist", "Arial", "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"],
          "fontSize": "35px",
          "fontWeight": 600,
          "lineHeight": "46.0687px",
          "letterSpacing": "-1.945px"
        }
      },
      "p": {
        "fontFamily": "Geist",
        "fontFallbacks": ["Geist", "Arial", "system-ui", "-apple-system", "Segoe UI", "Roboto", "Helvetica Neue", "sans-serif"],
        "fontSize": "16px",
        "fontWeight": 400,
        "lineHeight": "24px",
        "letterSpacing": "0px"
      }
    },
    "elementSpacing": {
      "xs": "2px",
      "sm": "6px",
      "md": "16px",
      "lg": "22px",
      "xl": "40px"
    },
    "shadows": {
      "sm": "rgba(0, 0, 0, 0.08) 0px 0px 0px 1px, rgba(0, 0, 0, 0.04) 0px 2px 2px 0px, rgba(0, 0, 0, 0.04) 0px 8px 8px -8px",
      "md": "none",
      "lg": "none",
      "xl": "none",
      "inner": "none"
    },
    "fontLinks": {
      "Geist": {
        "type": "google",
        "category": "sans-serif",
        "files": {
          "400": "https://fonts.gstatic.com/s/geist/v4/gyBhhwUxId8gMGYQMKR3pzfaWI_RnOM4nZPby1QNtA.ttf",
          "500": "https://fonts.gstatic.com/s/geist/v4/gyBhhwUxId8gMGYQMKR3pzfaWI_RruM4nZPby1QNtA.ttf",
          "600": "https://fonts.gstatic.com/s/geist/v4/gyBhhwUxId8gMGYQMKR3pzfaWI_RQuQ4nZPby1QNtA.ttf",
          "700": "https://fonts.gstatic.com/s/geist/v4/gyBhhwUxId8gMGYQMKR3pzfaWI_Re-Q4nZPby1QNtA.ttf"
        }
      }
    },
    "components": {
      "button": {
        "primary": {
          "backgroundColor": "#171717",
          "color": "#ffffff",
          "borderColor": "#ffffff",
          "borderRadius": "100px",
          "borderWidth": "0px",
          "borderStyle": "none",
          "padding": "13px 14px",
          "minWidth": "181px",
          "minHeight": "40px",
          "fontFamily": "Geist",
          "fontSize": "14px",
          "fontWeight": 500,
          "textDecoration": "none",
          "boxShadow": "none",
          "css": "background-color: #171717; color: #ffffff; border-radius: 100px; padding: 13px 14px; font-family: Geist; font-size: 14px; font-weight: 500;"
        }
      },
      "card": {
        "backgroundColor": "#fafafa",
        "textColor": "#171717",
        "borderColor": "#e5e7eb",
        "borderRadius": "8px",
        "borderWidth": "1px",
        "borderStyle": "solid",
        "padding": "16px",
        "boxShadow": "none",
        "css": "background-color: #fafafa; color: #171717; border: 1px solid #e5e7eb; border-radius: 8px; padding: 16px;"
      }
    }
  }
}

Field	Type	Description
`status`	string	`"ok"` on success.
`domain`	string	Normalized domain that was processed.
`code`	integer	HTTP status code.
`styleguide.mode`	string	`"light"` or `"dark"`: the page’s primary color mode.
`styleguide.colors`	object	`accent`, `background`, `text`: all hex strings.
`styleguide.typography.headings`	object	`h1`, `h2`, `h3`, `h4`: each has `fontFamily`, `fontFallbacks[]`, `fontSize`, `fontWeight`, `lineHeight`, `letterSpacing`.
`styleguide.typography.p`	object	Body text: same shape as a heading entry.
`styleguide.elementSpacing`	object	`xs`, `sm`, `md`, `lg`, `xl`: CSS length strings (typically `px`).
`styleguide.shadows`	object	`sm`, `md`, `lg`, `xl`, `inner`: full `box-shadow` declarations. `"none"` when no shadow at that tier.
`styleguide.fontLinks`	object	Keyed by font family name. Each entry has `type` (`google` or `custom`), `files` (weight → URL), optional `category` (Google only), optional `displayName` (custom only). Omitted when no family resolves to Google or `@font-face` URLs.
`styleguide.components.button`	object	Three variants: `primary`, `secondary`, `link`. Each variant has: `backgroundColor` `color` `borderColor` `borderRadius` `borderWidth` `borderStyle` `padding` `minWidth` `minHeight` `fontFamily` `fontFallbacks` `fontSize` `fontWeight` `textDecoration` `textDecorationColor` `boxShadow` `css`: ready-to-paste declaration block
`styleguide.components.card`	object	`backgroundColor` `textColor` `borderColor` `borderRadius` `borderWidth` `borderStyle` `padding` `boxShadow` `css`: ready-to-paste declaration block

Extract just the fonts

GET /web/fonts takes a domain (or a direct URL) and returns only the typography subset: every font family the site uses, with weights, fallbacks, usage counts, and downloadable file URLs.

curl -G https://api.context.dev/v1/web/fonts \
  -H "Authorization: Bearer $CONTEXT_DEV_API_KEY" \
  --data-urlencode "domain=vercel.com"

5 credits per successful call

Request Parameters

Either domain or directUrl must be provided, but not both.

Parameter	Type	Description
`domain`	string	Domain to extract fonts from (e.g. `vercel.com`). Normalized automatically.
`directUrl`	string (URI)	A specific URL to fetch fonts from directly, bypassing domain resolution.
`maxAgeMs`	integer	Max cache age before a hard refresh. Defaults to `7776000000` (90 days). Clamped to `[86400000, 31536000000]` (1 day – 1 year).
`timeoutMS`	integer (1000–300000)	Abort with a 408 if the request exceeds this many milliseconds. Max `300000` (5 min).

Response

{
  "status": "ok",
  "domain": "vercel.com",
  "code": 200,
  "fonts": [
    {
      "font": "Geist",
      "uses": ["body", "div", "header", "nav", "h1", "h2", "h3", "p", "button"],
      "fallbacks": ["Arial", "system-ui", "-apple-system", "Segoe UI", "Roboto", "sans-serif"],
      "num_elements": 534,
      "num_words": 9320,
      "percent_elements": 91,
      "percent_words": 99
    },
    {
      "font": "Geist Mono",
      "uses": ["code", "pre", "kbd"],
      "fallbacks": ["ui-monospace", "SFMono-Regular", "Menlo", "monospace"],
      "num_elements": 55,
      "num_words": 94,
      "percent_elements": 9,
      "percent_words": 1
    }
  ],
  "fontLinks": {
    "Geist": {
      "type": "google",
      "category": "sans-serif",
      "files": {
        "400": "https://fonts.gstatic.com/s/geist/v4/gyBhhwUxId8gMGYQMKR3pzfaWI_RnOM4nZPby1QNtA.ttf",
        "500": "https://fonts.gstatic.com/s/geist/v4/gyBhhwUxId8gMGYQMKR3pzfaWI_RruM4nZPby1QNtA.ttf",
        "600": "https://fonts.gstatic.com/s/geist/v4/gyBhhwUxId8gMGYQMKR3pzfaWI_RQuQ4nZPby1QNtA.ttf",
        "700": "https://fonts.gstatic.com/s/geist/v4/gyBhhwUxId8gMGYQMKR3pzfaWI_Re-Q4nZPby1QNtA.ttf"
      }
    }
  }
}

Field	Type	Description
`status`	string	`"ok"` on success.
`domain`	string	Normalized domain that was processed.
`code`	integer	HTTP status code.
`fonts[]`	array	One entry per font family on the page, ordered by usage.
`fonts[].font`	string	Primary face (first family in the computed stack).
`fonts[].uses[]`	array	CSS selectors or element types where this font is used.
`fonts[].fallbacks[]`	array	Fallback families from the computed stack.
`fonts[].num_elements`	number	Element count using this font.
`fonts[].num_words`	number	Word count rendered in this font.
`fonts[].percent_elements`	number	Share of all elements using this font.
`fonts[].percent_words`	number	Share of all words rendered in this font.
`fontLinks`	object	Optional. Same shape as `styleguide.fontLinks`: keyed by family with `type`, `files`, optional `category` and `displayName`. Omitted when no family resolves to Google or `@font-face` URLs.

Handle errors

A non-2xx response returns an { message, error_code, status } envelope. The common ones:

Status	`error_code`	Meaning	What to do
400	`INPUT_VALIDATION_ERROR`	Missing both `domain` and `directUrl`, or both were supplied	Pass exactly one.
401	`UNAUTHORIZED`	API key missing, invalid, or deleted	Re-check the env var and the dashboard.
408	`REQUEST_TIMEOUT`	Page didn’t render before `timeoutMS` (or 5 min default)	Retry once with backoff; the second hit usually succeeds.
500	`INTERNAL_ERROR`	Transient server error	Retry once with backoff; if it persists, contact support.

A 400 from omitting both domain and directUrl looks like:

{
  "status": "error",
  "error_code": "INPUT_VALIDATION_ERROR",
  "message": [
    { "code": "custom", "message": "Either directUrl or domain must be provided, but not both", "path": [] }
  ]
}

For the full catalog of error codes, see Troubleshooting.

Use cases

Next steps

Prefetch for Faster Response

Hide cold-hit latency from your users.

Handle Rate Limits

Backoff strategies, client cache, and prefetch fallbacks.

Best Practices

Caching, error handling, and key hygiene.

Troubleshooting

Status codes, retry patterns, and common errors.

​Prerequisites

​Extract the full styleguide

​Request Parameters

​Response

​Extract just the fonts

​Request Parameters

​Response

​Handle errors

​Use cases

​Next steps

Prefetch for Faster Response

Handle Rate Limits

Best Practices

Troubleshooting

Prerequisites

Extract the full styleguide

Request Parameters

Response

Extract just the fonts

Request Parameters

Response

Handle errors

Use cases

Next steps