Calque
Calque is free, open-source software that turns a website screenshot into working HTML and CSS by measuring pixels rather than asking a vision model to inter…
What Calque is
Calque is free, open-source software that turns a website screenshot into working HTML and CSS by measuring pixels rather than asking a vision model to interpret the image. It can produce a self-contained HTML file or a JSON specification of its measurements. The extracted details include colors, type scale, font weights, spacing, container width, gutters, and corner radii; it also identifies sections, columns, cards, buttons, alignment, and reading order. Calque can crop photographs from the screenshot for use as assets. Its check command renders the rebuilt page in an installed Chrome-family browser and compares it with the source screenshot pixel by pixel. It is packaged as a Claude skill that provides measurements for Claude to use when writing project code. The documented workflow uses Tesseract for OCR, with Docker as an optional container setup. Calque makes no model call or API request; after OCR data is cached, it works offline. It processes one screenshot at a time, cannot identify the exact typeface, and uses cropped images instead of recovering original photographs.
Good
- Free and open source under the MIT license.
- Outputs HTML or a JSON measurement specification.
- Extracts layout and design measurements.
- Can compare a rendered page with its screenshot.
Watch out
- Processes one screenshot rather than a whole site.
- Cannot identify the exact typeface.
- Uses cropped screenshot images, not original photographs.
- Photograph-heavy pages are a weak case.
Who it suits
Calque suits developers who want to rebuild a single screenshot as HTML and CSS, including those using Claude with supplied measurements. Its offline operation after OCR data is cached may suit users who want to avoid model calls and API requests.
Verdict
Calque turns a single screenshot into measured layout and style information, with HTML or JSON output and a browser-based pixel comparison. It has clear limits around typeface identification, original image recovery, and complex photographic or gradient-heavy pages.
The facts
Each one read from Calque's own pages, with the date it was checked.
What it does
- Claude integration
- Calque ships as a Claude skill that provides measured screenshot details for Claude to use when writing project code.checked 9 Oct 2026
- Design measurements
- It extracts design tokens including colors, type scale, weights, spacing, container width, gutters, and radii.checked 9 Oct 2026
- Image handling
- With the --assets option, it crops photographs from the screenshot and references those crops in the output.checked 9 Oct 2026
- Inputs and outputs
- It reads PNG or JPEG screenshots and can write a self-contained HTML file or a JSON file of measurements.checked 9 Oct 2026
- Known weak cases
- The maker reports lower reconstruction matches for photograph-heavy pages and identifies dark pages with large glows or gradients behind text as its worst case.checked 4 Oct 2026
- Layout and images
- It finds sections, columns, cards, buttons, alignment, and reading order, and can crop photographs from the screenshot as assets.checked 4 Oct 2026
- Layout features
- It identifies sections, columns, cards, buttons, alignment, and reading order, and can reconstruct vertical gradients.checked 9 Oct 2026
- License
- The repository is MIT licensed, and its README says users may take, host, fork, and sell it.checked 9 Oct 2026
- Limit: page coverage
- It reads one screenshot and does not capture scrolling, hover states, or another breakpoint.checked 9 Oct 2026
- Limits
- It processes one screenshot rather than a whole site, cannot identify the exact typeface, and uses cropped screenshot images rather than recovering original photographs.checked 4 Oct 2026
- Limit: typography
- Calque cannot identify a typeface from a screenshot, and font weight resolves to about one step.checked 9 Oct 2026
- Other tools
- The documented workflow uses Tesseract for OCR and Docker as an optional way to run Calque in a container.checked 4 Oct 2026
- Output
- It can write a self-contained HTML file or a JSON specification of its measurements.checked 4 Oct 2026
- Performance and accuracy
- The README says processing takes about a second per page and reports fixture match scores ranging from 15.3% to 97.1%.checked 9 Oct 2026
- Privacy and operation
- The maker says Calque makes no model call or API request, and that after its OCR data is cached it works offline; the Docker build preloads that data.checked 4 Oct 2026
- Purpose
- Calque turns a website screenshot into working HTML and CSS by measuring pixels rather than asking a vision model to interpret them.checked 9 Oct 2026
- Quality check
- Its check command renders the rebuilt page in an installed Chrome-family browser and compares it with the screenshot pixel by pixel.checked 4 Oct 2026
- Requirements
- The package specifies Node.js 20 or later; the README says the first run downloads about 15 MB of OCR data and caches it.checked 9 Oct 2026
- Runtime
- The maker says Calque runs in about a second per page and its tests run without network access.checked 4 Oct 2026
- Runtime and network
- The maker says the Docker build works offline after building, and that nothing else opens a socket.checked 9 Oct 2026
- Validation
- The check command renders the output in an existing Chrome-family browser and compares it with the screenshot pixel by pixel.checked 9 Oct 2026
Where it runs
- Limit: icons and photos
- Icons become placeholders, while cropped photographs remain screenshot-resolution images with any overlaid text baked in.checked 9 Oct 2026
The company
- Maker
- The repository says Calque is part of Openware, whose GitHub profile describes its work as self-hostable replacements for subscription software.checked 4 Oct 2026
Alternatives to Calque
- 1
Figma Make
Free planAndroidiOSWebAPI8.2Free plan - 2
v0
Free planiOSWebAPI7.8From $30 a month - 3
Kombai
Free planWebAPIExtensionLinux7.7From $20 a month - 4
CoderUI
Free planWebAPI7.2From $29 a month - 5
Builder.io
Free planWebAPIExtension7.1From $24 a month - 6
Alloy
Free planExtension6.9From $20 a month