HEIC to JPG

Since iOS 11, iPhones have saved photos as HEIC instead of JPEG. Apple switched because HEIC stores roughly the same picture in about half the space, which is a real saving across a few thousand photos. The cost is that HEIC is far less widely supported: Windows needs an extra codec installed, many upload forms reject it, and older Android phones and desktop apps often will not open it at all.

So the file is not broken and the photo is not corrupted. It is a modern format that the thing you are trying to use has not caught up with. Converting to JPG trades some file size for the ability to open it anywhere, which is usually the trade you want when you are emailing a photo, uploading it to a form, or handing it to someone else.

If you keep hitting this, fix it at the source rather than converting every time: on the iPhone, Settings → Camera → Formats → Most Compatible makes the camera shoot JPEG from then on. There is a second setting worth knowing about too — Settings → Photos → Transfer to Mac or PC → Automatic converts photos to JPEG as they come off the phone, while leaving the originals on the device untouched.

This converter runs entirely in your browser. Your photos are never uploaded, which is why there is no size limit, no queue, no watermark and no account — there is no server involved to impose any of them.