Open and view HEIC files
Drop a HEIC file and see it in the comparison panel below the tray, scaled to fit your screen. You do not have to download anything. If you want a JPEG afterwards, it is already made.
See what the quality setting does
Drag the line to compare the original with the JPEG at the quality you chose. The loupe shows a 3× crop under your pointer.
How this viewer works
Your browser decodes the HEIC into raw pixels and shows them on screen. As a side effect it also produces a JPEG, which is why a Save link appears. You can ignore it. Nothing is uploaded. Closing the tab discards your photo. The only things kept are the offline cache of the site itself and, if you have turned motion down, a setting named chj-calm in this browser’s local storage. No cookies are set.
Why Windows can't show HEIC thumbnails
Windows needs two components to read an iPhone HEIC: the free HEIF Image Extension, which may already be installed, and the paid HEVC Video Extensions, which is normally the missing one. Without both, File Explorer usually shows a blank icon and Photos can't open the file. The four ways to fix that.