How HEIC Photo Conversion Works

HEIC (High Efficiency Image Container) is the default photo format on iPhones running iOS 11 or later. It compresses better than JPG for the same visual quality, which is exactly why Apple made it the default — but most browsers, and a lot of software outside Apple's own ecosystem, can't decode it natively.

PDFPilot's HEIC to JPG and HEIC to PNG tools decode the file using a real HEIC/HEIF decoder (built on libheif, the same open-source decoding library used by several other HEIC tools) compiled to WebAssembly, so the actual decoding happens in your browser rather than on a server. The decoded image is then re-encoded as a standard JPG or PNG.

The first time you use either tool in a browser session, the decoder itself (a WebAssembly module) has to be loaded — after that it's cached, so later conversions in the same session are faster. Your photo itself is never uploaded anywhere; only the decoder code is a network request.

Choosing between the two outputs is straightforward: JPG is smaller and universally supported, the more practical default for sharing or uploading. PNG is lossless and supports transparency, at the cost of a larger file — worth it only if you specifically need pixel-perfect fidelity or transparency, neither of which a HEIC photo actually has to begin with.