Nothing opens your HEIC photos?
Your iPhone saves photos as .HEIC, and half the internet still refuses to open them. Drop them here and get PNGs back at full resolution, as many at once as you like. The decoder runs inside this page, so the photos are never uploaded, and their EXIF and GPS tags stay behind.
PNG is lossless, so a full-resolution 12-megapixel photo lands around 20–30 MB, roughly ten times the HEIC it came from. Shrink the long edge if you only need it for a message or a slide. Changing this re-converts everything.
Why won't anything open a .HEIC?
Since iOS 11, an iPhone photo is an HEIC file: a still frame of HEVC video (the codec also called H.265) wrapped in Apple's container. It is genuinely better than JPEG (about half the size at the same quality, with real transparency and 10-bit colour), but HEVC is covered by patent pools that charge for a decoder, so Windows, older Android builds, and plenty of web apps simply never shipped one. The file is fine. The thing you're opening just can't read it.
This page carries its own decoder: libheif, compiled to WebAssembly, running in the tab. It reads the photo, applies the rotation the container asks for, and hands the pixels to a canvas that writes a PNG, a format nothing has ever refused. Multi-image files (a burst, or the still frames Apple bundles alongside a Live Photo) come out numbered.
What gets lost on the way
PNG is lossless, so no pixel is thrown away. The file just gets much bigger, because HEIC's whole trick was compressing them and PNG doesn't. What does get dropped is the metadata: the capture time, the camera settings, and the GPS coordinates of the spot where you stood. That's usually the point. If you need those tags kept, this is the wrong tool.
An HEIC in 10-bit colour is flattened to the 8 bits per channel a canvas can hold. On a normal photo you will not see it; on a wide-gradient sunset you might.
Nothing leaves the page
There is no upload and no server. The decoder is 1.9 MB of WebAssembly fetched from this site the first time you drop a file, and after that everything (decoding, resizing, PNG encoding, even the ZIP) happens in your own browser. Open DevTools and watch the Network tab while you convert: the only request this page ever makes is a page-view ping that records the address /heic/ and nothing else. Your photos are not part of it.