iPhones save photos as HEIC by default (Settings, Camera, Formats, High Efficiency). HEIC files are small, but many websites, Windows apps and older editors will not open them. Converting to JPG is the usual fix.
Why not use an upload site?
Free HEIC converters usually upload your photos to a server. That is a lot of personal pictures to hand over for a format change. Here the conversion runs in your browser tab. The photos are not uploaded.
How to convert
Open the tool and drop your HEIC files, or pick them from your computer.
Leave the output on JPG. Choose PNG to avoid another lossy encoding step. For WebP, use the separate Image Compressor.
Quality 85 to 90 is a good start for photos you plan to keep.
Download single files or one ZIP.
What to know
The dedicated converter loads a local libheif decoder when you add a HEIC file. A sample from the libheif project was decoded in desktop Chrome; that is not proof that every iPhone variant works.
Large batches use a lot of memory. Phones have not been tested; try a small batch or a desktop computer.
Live Photos give you the still image only. HEIC files with several images (bursts) give you the first image.
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