Extract Design — Dembrandt

Dembrandt runs a headless Chromium browser against any URL, walks up to thousands of DOM elements, reads computed CSS, and returns a structured design system: colors with confidence scoring, typography styles, spacing scale, border radius, borders, shadows, and interactive component styles.

How to Run

# Zero-install — npx fetches the package on first run (lowest friction)
npx -y dembrandt https://dembrandt.com

# Or install once (global), then call `dembrandt` directly
npm i -g dembrandt

# Basic extraction — outputs to terminal
dembrandt https://dembrandt.com

# JSON output — pipe into files or other tools
dembrandt https://dembrandt.com --json-only > dembrandt-tokens.json

# W3C DTCG format (design-tokens.org standard)
dembrandt https://dembrandt.com --dtcg --save-output

# Generate DESIGN.md (human + AI readable brand doc)
dembrandt https://dembrandt.com --design-md

# Multi-page crawl (follows internal links)
dembrandt https://dembrandt.com --crawl 5

# Dark mode colors
dembrandt https://dembrandt.com --dark-mode

# Mobile viewport
dembrandt https://dembrandt.com --mobile

# Everything saved to output/
dembrandt https://dembrandt.com --save-output

# Tailwind v4 @theme CSS — observed values only  [dembrandt 0.28+]
dembrandt https://dembrandt.com --tailwind src/app.css

# Self-contained HTML report — open offline or attach as a CI artifact  [dembrandt 0.19+]
dembrandt https://dembrandt.com --html report.html

# Drift gate — compare against a saved baseline; exits 1 on drift  [dembrandt 0.19+]
dembrandt https://app.example.com --compare baseline.json --html report.html

MCP Usage (async by default)

To expose Dembrandt as MCP tools, add this server to the agent's MCP config (no install — npx fetches it on first run):

{ "mcpServers": { "dembrandt": { "command": "npx", "args": ["-y", "--package", "dembrandt", "dembrandt-mcp"] } } }

When using the Dembrandt MCP server, all extraction tools return a job_id immediately rather than blocking. Poll get_job_status until status is "completed":

1. get_design_tokens({ url: "dembrandt.com", pages: 5 })
   → { job_id: "job_123_abc", status: "queued" }

2. get_job_status({ job_id: "job_123_abc" })
   → { status: "running" }   // poll again

3. get_job_status({ job_id: "job_123_abc" })
   → { status: "completed", result: { ... } }

4. get_findings({ job_id: "job_123_abc" })      // no need to resend the extraction
   → { findings: [ ... ], contrast: { ... } }

Hand the job_id to the analysis tools instead of passing the extraction back. Every pure tool accepts it, and the queue keeps the whole extraction for an hour, so a job started by a narrow tool such as get_color_palette still feeds export_dtcg. Passing the extraction inline works and wins when you give both, but a real extraction is far too large to travel back through the model as a tool argument. [dembrandt 0.29+]

Pass sync: true to any extraction tool to block and return the result directly (useful on fast networks, risks timeout on slow sites, and proportionally slower when pages is above 1).

Extraction tools: get_design_tokens (everything), get_color_palette, get_typography, get_component_styles, get_surfaces, get_spacing, get_brand_identity. All accept slow, mobile (mobile viewport), and cookie (cookie string for authenticated pages); get_design_tokens and get_color_palette also accept darkMode and wcag (contrast analysis). [dembrandt 0.23.1+ for mobile/cookie/wcag]

Every extraction tool also crawls, which is the single biggest lever on token quality: one page gives you one page's tokens. [dembrandt 0.29+]

Option	What
pages	Extract up to N pages and merge them into one token set (1 to 20). Pages come from DOM links, or from sitemap.xml when sitemap is true
paths	Name the extra paths explicitly, e.g. ["/pricing", "/docs"]. Overrides discovery
sitemap	Discover from sitemap.xml. Alone it takes up to 20 pages; pages caps it
header	One extra HTTP header, e.g. "Authorization: Bearer ...", for pages a cookie cannot reach
userAgent	Custom user agent string
noSandbox	Disable the browser sandbox. Required inside Docker and most CI containers, where launch otherwise fails

A page that fails to load is dropped and the merge carries the rest, so a crawl does not fail on one bad URL.

Pure tools (no browser, synchronous; take an extraction object, or the job_id of a completed one [dembrandt 0.29+]): compute_drift (0-100 drift score between two extractions; takes baselineJobId and candidateJobId as the job-based form), get_findings (design-system lint: contrast, consistency, duplication), export_dtcg (W3C Design Tokens format), generate_design_md (DESIGN.md brand guide), render_report (self-contained HTML report). Job control: get_job_status, list_jobs, cancel_job. [dembrandt 0.23.1+ for get_findings/export_dtcg/generate_design_md/list_jobs]

Note: npx runs a dembrandt-mcp already on PATH in preference to the version named in --package, so a globally installed dembrandt silently shadows the pinned one. Symptom: options the pinned version supports are rejected as unknown, or a crawl returns a single page. Check with dembrandt --version and upgrade the global install, or point the MCP config at an explicit path.

Note: dembrandt <=0.23.0 fails to start via the npx one-liner above (McpDepsMissingError) — the MCP SDK was an optional peer dependency. Fixed in 0.23.1; require it.

Output Structure

Dembrandt returns a structured object. The key sections:

colors.palette        — Deduplicated colors with confidence (high/medium/low).
                        Each entry carries hex (`normalized`), plus `lch` and
                        `oklch` of the same colour, and derived `role`,
                        `onColor`, `hover`. With `--wcag`, entries also carry
                        `contrastAgainst`, the pairs this colour was actually
                        observed against on the page, deduped by the other
                        colour and sorted by ratio (dembrandt 0.31+).
colors.semantic       — Primary, secondary, background, text, and accent detection
colors.cssVariables   — Named CSS custom properties. `value` is the author's
                        string verbatim (the only record of the authored
                        notation), plus computed hex + LCH + OKLCH.
typography.styles     — Font family, size, weight, line-height per context.
                        Each entry carries `count`, the number of elements
                        rendering that exact style.
typography.sources    — Google Fonts, Adobe Fonts, variable font detection.
                        `urls` lists the resolved font asset and webfont
                        stylesheet URLs, deduped, so you can re-fetch or verify
                        the real files. `filteredFamilies` lists families
                        dropped by the usage floor — check it before concluding
                        a face is missing.
spacing.commonValues  — Margin/padding scale with rem equivalents
spacing.scaleType     — 4px, 8px, or custom grid
borderRadius.values   — Border radius tokens with element context
borders.combinations  — Width + style + color combinations
shadows               — Box shadow elevation system
components.buttons    — Button variants with hover/active/focus states
components.inputs     — Input styles with focus states
components.links      — Link colors and hover states
components.badges     — Badge/tag/chip variants
breakpoints           — Responsive breakpoints from CSS media queries
frameworks            — Detected CSS framework (Tailwind, shadcn, MUI, etc.)
iconSystem            — Detected icon library (Heroicons, FA, Material, etc.)
pages                 — Present only on a merged multi-page result (`--crawl`,
                        `--sitemap`, extra paths, or MCP `pages`). One entry per
                        page extracted, so you can tell which URLs the merged
                        tokens came from. Palette entries then also carry
                        `pageCount`.
wcag                  : with `--wcag`, observed contrast pairs (fg, bg, ratio,
                        aa/aaLarge/aaa booleans) between real rendered colours.
meta.crawl            : present when `--crawl`, `--sitemap` or explicit paths
                        are used, with `technique`, `pagesRequested`,
                        `pagesFound` (dembrandt 0.31+).
meta.robotsWarnings   : pages robots.txt disallowed, whether that was the
                        entry URL or one discovered during a crawl. The check
                        is advisory, it never blocks extraction, this is the
                        only record of what it flagged (dembrandt 0.31+).

Working with Extracted Tokens

Seeding a Tailwind theme (dembrandt 0.28+)

Don't hand-map the JSON. --tailwind writes a Tailwind v4 @theme block directly:

dembrandt https://dembrandt.com --tailwind            # → output/<domain>/theme.css
dembrandt https://dembrandt.com --tailwind src/app.css  # or straight into the project

@import "tailwindcss";

@theme {
  --color-primary: #ea580c;
  --text-display: 96px;
  --text-display--line-height: 1;
  --spacing: 8px;
  --radius-lg: 8px;
  --breakpoint-md: 700px;
}

Observed values only: no 50–950 shade ramps, no interpolated scale steps, no derived hover or on-colour variants. An invented shade is indistinguishable from a measured one once it is in the file, so the export is a starting point you extend by hand. Colours keep their semantic role name (--color-primary) or the page's own custom property name where one is declared; the rest are numbered --color-brand-N. Spacing collapses to v4's --spacing multiplier when the page has a base-N rhythm, and falls back to named steps otherwise. Tailwind's defaults still apply to anything not listed, so the block extends the theme rather than replacing it.

v4 only. For a v3 tailwind.config.js, map the output by hand — colors.semantic → theme.colors, typography.styles → fontFamily, spacing.commonValues → spacing, borderRadius.values → borderRadius, shadows → boxShadow.

Seeding a shadcn/ui theme

Map semantic colors to shadcn CSS variables in HSL:

:root {
  --background: /* from colors.semantic.background (0.22.0+), else colors.palette — lightest neutral */;
  --foreground: /* from colors.semantic.text (0.22.0+), else colors.palette — darkest neutral */;
  --primary: /* from colors.semantic.primary */;
  --primary-foreground: /* contrasting color */;
  --muted: /* mid-tone neutral */;
  --border: /* from borders.combinations[0].color */;
  --radius: /* from borderRadius.values[0].value */;
}

Reading confidence levels

Dembrandt scores every color by semantic context:

Confidence	Meaning
high	Appears on semantically labeled elements (buttons, CTAs, headers with brand classes). Almost certainly a brand color.
medium	Moderate frequency or moderate context. Likely a brand color.
low	Rare, low semantic context. May be a one-off or component-specific color.

Since 0.28.0 confidence also has a usage floor, as spacing and radii always had: a colour seen once caps at low, twice at medium, and high needs three occurrences whatever its semantic context scores. Hover and focus colours are the exception and keep medium — their single occurrence is provenance, not a usage claim.

Start with high confidence colors when building a palette. Include medium for full coverage. Treat low as reference only.

Colour notation

Never convert a colour by hand and never re-derive one with your own maths. Every palette entry and every CSS variable already carries lch and oklch alongside the hex, so read the field you need straight from the JSON. --color-format only changes what the terminal prints, so it is the wrong tool when you are consuming JSON or MCP output.

Use hex (normalized) as the identity of a colour: it is what dedup, drift comparison and every downstream tool key on. Two entries with the same hex are the same token even when their emitted notations differ. When an author declared a token in a modern notation, cssVariables[name].value preserves it exactly, which is what you want when writing CSS back into that codebase, since it keeps the author's own notation and stays inside their gamut.

Flags Reference

Flag	What it does
--json-only	Clean JSON to stdout — pipe into files or tools
--save-output	Save JSON to output/<domain>/<timestamp>.json
--dtcg	W3C Design Tokens Community Group format
--design-md	Generate DESIGN.md — prose-first brand doc
--html [path]	Self-contained HTML report (inline CSS, embedded JSON). Open offline or attach as a CI artifact. (0.19+)
--compare <baseline.json>	Diff against a saved extraction; prints a drift verdict and exits 1 on drift. CI gate. (0.19+)
--brand-guide	Generate a PDF brand guide
--dark-mode	Extract dark color scheme and merge into palette
--mobile	Extract at 390px mobile viewport
--crawl <n>	Crawl up to N pages and merge tokens
--sitemap	Discover pages from sitemap.xml
--slow	3× timeouts — use on slow-loading or JS-heavy sites
--screenshot <path>	Save a full-page screenshot
--raw-colors	Include pre-filter raw colors in JSON output
--color-format <fmt>	Notation for colors printed to the terminal: hex (default), rgb, oklch, lch, source (as authored). Presentational only, so JSON output is unchanged, and export paths ignore it. (0.28+)
--tailwind [path]	Write a Tailwind v4 @theme CSS file — observed values only. Defaults to output/<domain>/theme.css. (0.28+)
--browser firefox	Use Firefox instead of Chromium
--stealth	Opt-in anti-detection: navigator spoofing + human mouse simulation. Use only when authorized.
--user-agent <string>	Custom user agent string
--locale <string>	Browser locale, e.g. fi-FI, en-GB (default: en-US)
--timezone <string>	Browser timezone, e.g. Europe/Helsinki (default: America/New_York)
--accept-language <string>	Custom Accept-Language header value
--screen-size <WxH>	Physical screen resolution to report, e.g. 1920x1080

Drift Detection & CI (dembrandt 0.19+)

--compare turns extraction into a gate. Save a known-good baseline, then compare later extractions against it:

# 1. capture a baseline (in the SAME environment you will check against)
dembrandt https://app.example.com --json-only > baseline.json

# 2. later — compare; exits 0 if stable, 1 if drifted
dembrandt https://app.example.com --compare baseline.json --html report.html

• Runs the canonical drift engine over structured tokens — deterministic, not a pixel/render diff.
• Exit code: 0 stable, 1 drift. Gates a pipeline directly.
• --html writes a self-contained report; with --compare it includes a drift banner (added/removed/changed tokens). Attach it as a CI artifact.

Baselines churn once on 0.28.0. Three fixes move colour and typography values: the palette usage floor, body ending at the 24px reading range (non-heading text above it takes text, so hero copy stops landing on the body token), and families under 2% of counted text being dropped. Measured on dembrandt.com against a 0.27.1 extraction, drift came out at 15 against a threshold of 10 — enough to fail a gate. On the first run after upgrading, re-approve with --compare <baseline> --approve or regenerate the baseline. Drift after that is real drift.

Determinism: capture the baseline in the same environment you check it in (both production, or both the same preview). A baseline from one environment compared against another shows false drift.

In CI: run --compare <baseline> --html report.html against a preview/deployed URL, fail the job on exit 1, upload the HTML artifact. Programmatic: import computeDrift from dembrandt/drift and generateHtmlReport from dembrandt/report to diff and render server-side without the CLI.

Anti-Bot and SPA Handling

Dembrandt handles common extraction challenges automatically:

• SPA hydration — waits 8s for React/Vue/Svelte to render before extracting
• Lazy content — scrolls the full page to trigger lazy-loaded components
• Cloudflare / bot walls — auto-retries with a visible browser if headless is blocked
• Slow sites — use --slow for 3× timeouts on heavy JS bundles
• Cookie banners — dismisses common CMP dialogs (OneTrust, cookielaw, GDPR patterns) automatically
• Bot detection bypass — use --stealth to opt in to navigator spoofing and human mouse simulation; off by default so the tool identifies itself honestly

Checklist After Extraction

• Identify the 3–5 high-confidence colors — these are the core brand palette
• Check colors.semantic.primary — is it correct?
• Look at typography.styles — what are the heading and body fonts?
• Check spacing.scaleType — 4px or 8px grid?
• Review components.buttons — how many variants exist?
• Check frameworks — is Tailwind, shadcn, or MUI detected? This shapes how you apply the tokens.
• Use --dark-mode if the site has a dark theme
• Use --crawl 3 if the site has a multi-section design system spread across routes