Capture a long page as a phone sees it

Setting width to 390 gets the media queries right, but the page still sees a desktop browser: no touch, a desktop user agent and a density of 1. Sites that serve different markup or images to phones show their desktop version squeezed into a narrow window.

Use the mobile preset

device: "mobile" sets a 390 by 844 viewport, a device pixel ratio of 3, touch and a phone user agent together. An explicit width, height or device_scale_factor still wins, which is how the request below keeps the phone layout at a density of 2.

curl -sS https://api.ironfang.com/render/v1/screenshot \
  -H "Authorization: Bearer $IRONFANG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://ironfang.com/company",
    "device": "mobile",
    "device_scale_factor": 2,
    "full_page": true,
    "full_page_readiness": "scroll",
    "format": "jpeg",
    "quality": 80
  }' \
  -o company-mobile.jpg

• company-mobile-full.jpg: the whole capture, as the request above returned it on 13 October 2026

Keep the output a usable size

The image is the page height times the density. At the preset density of 3, a page 19,070 CSS pixels tall comes back 57,210 pixels tall, which many image viewers and upload limits refuse. For archives and review, a density of 1 or 2 is usually enough.

WebP cannot hold an image taller than 16,383 pixels, so use JPEG or PNG for long captures. JPEG keeps a tall capture small; PNG is lossless.

Cap pages with no natural end

A feed that keeps loading has no bottom. full_page_max_height cuts the capture at a height in CSS pixels, 20,000 at most and by default, and the X-Ironfang-Warnings header says height_capped when it does.

{
  "url": "https://example.com/feed",
  "device": "mobile",
  "full_page": true,
  "full_page_max_height": 8000,
  "format": "jpeg"
}

Sticky headers and fixed bars

The capture is taken from the top, so a sticky header appears once, at the top, and a fixed bar sits where it was in the first screen. Hide either with hide_selectors, and consent banners with block_cookie_banners.