Apple’s format, everyone else’s problem
Since iOS 11 an iPhone saves photos as HEIC by default. Inside Apple’s world nothing seems unusual: the pictures open, share and print without comment. The trouble starts the moment a file leaves that world. It lands on a Windows machine that wants a codec, in an application form that only lists JPG and PNG, or in a colleague's inbox where it simply will not preview.
This page converts them where the photos already are. Safari can decode HEIC by itself, so on an iPhone or Mac the work is done by the browser you are already using. Other browsers cannot, so the page fetches a decoder the first time you actually pick a HEIC file, and never before that. Either way the photo stays on your device from start to finish.
Worth knowing before you convert
- Orientation is handled. Photos taken sideways come out upright rather than rotated.
- Live Photos lose the motion. Only the still frame is converted; JPG has nowhere to keep the video part.
- The JPG will be larger. HEIC compresses better, so compatibility costs some megabytes.
- Keep the originals until you have checked. Convert, open one result, then tidy up.
If the photos are pages of a document rather than pictures, converting them individually is the long way round. JPG to PDF takes the converted files and turns the whole stack into one PDF in the order you choose, which is what most portals actually ask for.