Apps similar to QuickLook include Preview, which is free. Other options are Seer Pro, Eye of GNOME, WinQuickLook and GNOME Sushi. You can choose from more than 10 Image Viewers like QuickLook for Mac, Windows, Linux, iPhone and iPad.
QLStephen is an Apple OSX Quick Look plugin that lets you view plain text files without a file extension. It is useful for reading files like README, INSTALL, CHANGELOG, Makefile, Rakefile and CapFile (files that the default Quick Look plugins don't handle).
Folder Preview is a Quick Look extension that lets you preview the contents of a folder.
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eom or the Eye of MATE is a simple graphics viewer for the MATE desktop which uses the gdk-pixbuf library. It can deal with large images, and can zoom and scroll with constant memory usage. Its goals are simplicity and standards compliance. Eye of MATE is a fork of Eye of GNOME.
Simple macOS PDF reader with ChatGPT integrated. You can chat with your local PDF. The returned response can cite the page number to ensure correctness.
Scoopy quick inside manipulation of windows folders with excessive (optional?) features but useful preview on paid version. The website is up to date (Nov 2018).
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A plugin that lets you view HEIC photos on Windows and convert them to JPG by right-clicking.
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Redact & Annotate images. Hide or mark up essential parts of your image by simply clicking and dragging on it.
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When Quick Look spacebar preview of your Mac doesn't work and you end up with the thumbnail of the photo, you can use Quick Look Fix from the menu bar.
