100% Private100% PrivateImage Guide
iPhones save photos as HEIC by default, which is smaller than JPG but not accepted by many blogs, stores, and form uploads. Converting HEIC to JPG or WebP makes those photos usable everywhere.
Upload your HEIC files in the browser and choose JPG for maximum compatibility, or WebP for smaller files on modern sites. PNG is there if you need it, but it will be larger.
HEIC decoding depends on your browser. Safari handles it best, because Apple built the format. Chrome and Firefox may report a failure for a HEIC file, and that is by design in v1, not a bug in your photo. Try Safari if a file fails elsewhere.
Convert before you resize or compress. A converted JPG or WebP can then go through the normal bulk compressor, resizer, or target-size tool like any other image.