Features

Viewing

Zoom, fit, 1:1, fit the width (H) or the height (W) or fill the view for every image, zoom kept between images, full screen, rotate, mirror and flip.
Layouts with two or four images at once, and Compare (E) side by side at the same zoom.
A projector window for a second screen: only the image, following the slideshow and the zoom, with a ring where you point.
Slideshow with random order, repeat, all subfolders, several folders at once (glimt --slideshow ~/Holiday ~/Family), and every pane of a layout.
Histogram, information over the image from a template of your own, an EXIF panel and a window with every EXIF field.
Colour-managed: photos with Adobe RGB or Display P3 profiles are shown as they should be.

Select by dragging a rectangle over the icon grid, or with Ctrl and Shift.
Fuzzy search on file names, and search in EXIF, keywords and comments, combined with and, not, or and groups: sunset ( exif:canon | exif:nikon ) -re:png$.
Sort by name, number, date, EXIF date, size or extension.
Marks 1–6 and 0–5 stars, keywords and a comment for each image, and a keyword tree (Places → Norway → Oslo) whose levels darktable, digiKam, Lightroom and Immich read.
Collections: lists of images from any folders, saved, renamed and opened again, in an order you set by dragging them in the file list (or Ctrl+Shift+↑ and ↓) for the slideshow; a plain list you write (.txt, .m3u) plays in its order.
Lightroom Classic catalogs imported: collections, the keyword tree, stars and each image's keywords.
Check Images: finds broken files, photos cut off in copying and files that are no image, and marks them in the list.
Find Duplicates: identical files, the same name, size or dimensions, or similar pictures.
The sort manager: move or copy images to favourite folders with one click.
Pan view: every image in the folder as a timeline of thumbnails by day, or as a calendar.
Screen readers such as Orca read the menus, lists and each image, with its alt text; menus, lists and text from 50 to 300 %, larger with GNOME's Large Text; High Contrast when the desktop asks for it.

Copy, move, rename (many at once with a pattern), delete to the trash; the status bar counts the files as they go, with a Stop button, and marks and stars follow the files.
Save the rotation to the file. Copy images or paths to the clipboard, open them with another application, and print them to any CUPS printer or a PDF, one per page or as a contact sheet.
Plugins: run any command on the selected images from the Edit menu.
Open a folder with all its subfolders (File → Open Folder Recursive…), or several folders as one list.
Back up Glimt's own data (marks, stars, collections, keyword tree) to a folder you choose.
For a shared computer, --lock-settings (or /etc/glimt/lock-settings) keeps the settings as they are.
Remote control from scripts and desktop shortcuts: glimt --remote next (see Command line).
Scripts and AI assistants can ask what is shown and selected, and a plugin can describe photos with a model on your own computer (see Scripts and AI).

Everyday: JPEG, PNG, WebP, GIF, TIFF, BMP, ICO, QOI and PNM, with animated GIF, WebP and PNG playing in a loop, frame by frame with Ctrl+Page Down and Up, a frame saved or all exported, and every page of a multi-page TIFF.
Science: grey TIFFs of floats or signed numbers (height models, microscopy), stretched to show, Zeiss .lsm from microscopes and .gel gel scans.
Through decoder plugins (Glimt 0.24.0): DICOM (also compressed), NIfTI, whole-slide pathology, microscope files through Bio-Formats, cryo-EM (MRC), FITS (also .fits.fz), HDF5, NetCDF-4 and NeXus, JPEG 2000, Photoshop, TGA, OpenEXR and GIMP. Each is a small file in ~/.local/share/glimt/decoders that names a program you have; see Plugins and formats.
Camera RAW: CR2, CR3, NEF, ARW, ARQ, DNG, GPR, ORF, RAF, RW2, RAW, PEF and more, shown at once through the JPEG preview the camera stores in them: Canon, Nikon, Sony, Fujifilm, Olympus and OM System, Panasonic, Leica, Pentax, Samsung, Hasselblad, Phase One, GoPro, and phones that save DNG.
Modern formats: HEIC/HEIF from phones, AVIF, JPEG XL, SVG, and Radiance HDR, tone-mapped to the screen.
Video: a still frame in the list and the viewer; opening it plays it in your video player.
Colour: photos with an ICC profile are converted to sRGB, so they do not look dull, or to your screen's own profile for a calibrated or wide-gamut screen, taken from the desktop (colord) when it has one.

HEIC, AVIF and video need ffmpeg installed.