CoolCroco

CoolCroco decodes the whole folder to display resolution on background workers
and holds it in RAM, so navigating in both directions is instant after the first
pass -- no per-image re-decode, no cache flushing.

Reads all the major RAW formats (Sony, Canon, Nikon, Fujifilm, Olympus,
Panasonic, Pentax, Leica and more, via LibRaw) plus HEIC/HEIF, JPEG, PNG, TIFF
and WebP.

Whole-folder cache with 2:1 prefetch; zoom and pan with sticky zoom across
frames; full-res decode-on-zoom for true 1:1 peeping; thumbnail filmstrip;
keep/reject culling into Approved/ and Rejected/ subfolders with undo; EXIF in
properties and selective EXIF removal with a restorable backup; focus and
camera-shake detection; timelapse/burst detection; IPTC metadata writing;
search by picture content; customizable shortcuts.

Photos on an SD card or external drive need the removable-media permission,
which you can grant in App Center under this app's Permissions.