Dezoomify

Desktop app

Use desktop for images beyond browser limits, local sources, or more output formats. It runs on Windows, macOS, and Linux and saves directly to your chosen folder. It cannot reuse your browser login; use the extension for signed-in pages.

The app can build the output file while downloading, without keeping the whole image in memory. Memory use depends on the source and output format; WebP and AVIF still need the complete picture in memory. If a save reaches a limit, choose another format, a smaller resolution, or a tile folder.

Image information and every image piece are downloaded through your own internet connection. This can help when a source site blocks Dezoomify’s shared server.

Resuming an interrupted save

Run the same job again to reuse cached tiles. The cache is enabled by default; choose a custom folder in settings or with CLI --tile-cache. If the source image changed, remove its cached tiles first. Cached tiles do not contain your browser session.

Recent pictures

History keeps your last 20 started images on this device. Click a saved filename under Result to open its file; missing files show Deleted. Click Source to fill the address field without starting. Remove entries with the trash icon or Clear history; this never deletes saved images.

Saving and opening images

Choose the folder, format, and size on the main screen, paste an address, and start. Saving is automatic. When Image saved appears, use Open image or Show in folder. Settings return on the main screen, not the result screen. Pause stops new tile downloads; Cancel remains available while output finishes.

Install

The releases page ships installers for Linux x86_64 (.deb), Windows x86_64 (.msi), and Apple silicon macOS (.dmg). Linux and Windows installers are unsigned. macOS releases use a Developer ID signature and Apple notarization. The operating system may ask you to confirm that you want to open a downloaded app.

Choose Help → Check for updates… to check GitHub Releases. The app asks before downloading a signed update and restarting. Finish or cancel any current save first. Linux and Windows may ask for administrator permission to install the update. Older versions without this menu need one manual upgrade to gain the updater.

You can also build the app locally with cargo xtask build desktop, which produces an installer for the matching host under target/release/bundle/ (Linux .deb on a Linux host with the webview system packages; Windows .msi and macOS .dmg only on their matching hosts). Local macOS builds use an ad-hoc signature unless Apple signing credentials are supplied; these builds are not notarized by default.

Opening the macOS app

Download the .dmg from the releases page and open it. The installation window displays these steps beside the app and Applications icons:

  1. Drag Dezoomify into Applications.
  2. Open Dezoomify from Applications.
  3. If macOS asks whether to open this downloaded app, click Open.

Official macOS releases are signed and notarized. Only open a download you trust.

Older releases and local ad-hoc builds may require approval under System Settings → Privacy & Security → Open Anyway. See Apple's instructions.

If macOS instead says the app is damaged, will damage your computer, or has been moved to Trash, download a fresh copy from the releases page. If it still fails, report the exact warning (or a screenshot), your macOS version, and the release filename in a GitHub issue. A damaged-app warning can indicate a packaging or signature problem; automatic movement to Trash can indicate malware detection. Do not assume either warning is the ordinary developer-approval prompt.

Save an image

Paste the viewer page or image description address and start dezooming. The app names the output from the image title and adds a numeric suffix if needed; existing files are preserved. Copy an address from the website to continue here. For terminal use, see the CLI guide.

If a server accepts requests only from its viewer, add that page as the Referer header in settings. See access refusals. This does not sign you in or transfer your browser session.

Choosing the file format

  • Auto chooses JPEG for an opaque image within JPEG's dimensions, otherwise PNG.
  • PNG or TIFF are lossless choices for archiving and editing.
  • JPEG suits smaller on-screen copies; it is limited to 65,535 pixels per side.
  • WebP is lossless here, but needs a complete pixel buffer and is limited to 16,383 pixels per side.
  • AVIF saves lossy images with transparency, up to 65,535 pixels per side. It needs the complete image in memory and does not preserve embedded color profiles. Quality 100 is not a lossless mode.
  • ZIF is a tiled multi-resolution image and omits transparency.
  • IIIF saves a folder with info.json and tiles for a static web viewer.

The Compression slider at the top of the Size menu updates the size budgets as you drag it. Its value passes unchanged to the encoder: higher compression aims for smaller files, and each format decides the tradeoff in detail and encoding time. The slider is disabled when the format cannot adjust compression. An amber warning marks very low lossy quality, where text and fine details may become unreadable. The cutoff is a guideline; the effect depends on the image. Compatible IIIF/ZIF tiles keep their original compressed bytes.

Size estimates assume an image filling the selected maximum dimensions; smaller sources or different aspect ratios can produce much smaller files. They use the chosen format and compression to give a rough budget, not a guaranteed file-size or memory limit. Auto assumes an opaque JPEG.

Settings

Choose an output folder, format, compression, optional size caps, retry budget, cache folder, and request headers. Settings persist on this device. Invalid values are refused rather than starting a job with them.

If a save fails

Read the error's suggested next step. After automatic retries are exhausted, the download pauses and offers Retry once more or Cancel. Retrying keeps successfully downloaded tiles; the app waits for your answer without a timeout. Permanent tile failures or cancellation stop the job without publishing an incomplete image. Restarting the job can reuse good cached tiles; see resuming.

If opening a saved file fails, try Show in folder. Use Technical details & logs for a report, reviewing sensitive addresses and settings before sharing.

Next steps