Screenshot2HTML od J.W

The built-in screenshot tool of Firefox is too limited? Try this one!

Features:
- unlimited capture area (auto-split)
- images in PNG or JPEG format
- selectable text embedded like PDF (rudimentary implementation)
- support for right-to-left scrolling
- single HTML + images = maximum portability
- functioning on even Firefox version 52
- no network connection required (capture only static content, no JavaScript nor CSS stylesheets)

Caveats:
- The maximum dimension of PNG images is 2147483647x2147483647.
- The maximum dimension of JPEG images is 65535x65535.
- Screenshot may be split into multiple images due to various limits.
- Screenshot on some pages may be forbidden by the browser.
- Scrollable contents in sub-frames may not be captured in full.
- Glitches may happen on animated or dynamically generated contents.
- Glitches may happen when some CSS rules or filters are applied.
- Processing zoomed-in pages may take up a great amount of RAM space.
- Large screenshots trade compression ratio for speed of generation.
- Firefox version 81 and earlier use less effective capturing methods.

If you don't want to miss dynamically generated web content, then:
- Take screenshots after scrutinizing the whole page.
- Visit about:config and set dom.image-lazy-loading.enabled to false.

It is recommended to view the HTML screenshot using one of the best image viewers — Firefox :-)

If you want the whole screenshot saved as a single image, please try this experimental extension: Infinite Screenshots

Screenshot in AVIF image format will be supported in the future, which enables cross-platform super large single-file screenshot.