How this works: this page uses an open-source WebAssembly build of libheif to decode HEIC/HEIF images directly in your browser tab, then re-encodes them to JPG or PNG using the browser's own canvas. Your photos are never sent to any server.
Troubleshooting
The converted image looks washed out or the colors look slightly off
Some HEIC photos are saved with a wide-gamut (Display P3) color profile. Converting to JPG re-encodes through the browser's canvas, which can shift color slightly at lower quality settings. Try moving the quality slider closer to 1 for the most faithful result.
I selected a file but nothing converts
Confirm the file is actually a .heic/.heif container. Some cameras and apps label an already-JPEG file with a .HEIC extension (the Image Metadata & EXIF Viewer will tell you the file's real format if you're not sure), and a Live Photo is really two separate files (a HEIC image plus a .mov clip) — make sure you picked the image, not the video half.
Prefer the command line?
Needs an ImageMagick build with HEIC/HEIF delegate support. On a Mac, sips also works out of the box: sips -s format jpeg input.heic --out output.jpg.