HEIC to JPG converter — open iPhone photos anywhere, without uploading them

HEIC is an excellent camera format trapped inside an Apple-centred ecosystem. iPhones use it because it stores a photograph in roughly half the bytes of JPEG, but Windows Explorer, many Android apps, printers and older government upload widgets still treat the file as unknown. The photograph is not corrupt; the receiving software simply does not include an HEVC image decoder.

The usual workaround — uploading a private family photograph to an unfamiliar converter — is disproportionate. This page downloads a standards-based HEIC decoder once, decodes the pixels in the browser tab and encodes a fresh JPG locally. Open the Network tab while it runs: no request carries your image anywhere.

Conversion is also the right first step before an exam or identity-form upload. Portals expect JPG even when a phone supplies HEIC, and converting first lets you check the photograph visually before resizing it into a strict pixel and KB window.

Format rejection is the least informative failure a portal can hand you: the upload simply does not appear, or returns a generic error, because the file header says WebP or HEIC while the requirement says JPEG. Converting is a thirty-second fix that removes a whole class of dead ends.

The reverse case matters for the web. Serving WebP or AVIF instead of JPEG typically saves a quarter to half the bytes for the same visual quality, which is free page-speed improvement for anyone with a website or blog.

Conversion is one of the few operations where doing it in the browser is not merely a privacy nicety — passing a photograph through an unknown converter often adds a watermark or silently shrinks it, and neither happens here.

This tool exists for images handled in a hurry: no queue, no account, no upload, and a result you can verify on the spot. The explanation below is the same one we would give a colleague who asked how it works.

Pixels, DPI metadata and physical print size are distinct. For example, 35 mm at 300 pixels per inch is approximately 413 pixels, but pixels alone cannot guarantee a printer produces a 35 mm image. If the instructions also require DPI metadata or a measured print, check those separately.

On a phone, memory is the real constraint rather than any size limit. A 12-megapixel photograph is about 36 MB once decoded into pixels, so compiling a batch of twenty and holding every result in memory at once will get a mobile browser killed well before it runs out of storage. Process batches of ten to fifteen on a phone; on a laptop the same job is unremarkable.

Accepted inputs are JPEG, PNG, WebP, AVIF, HEIC, GIF and BMP images up to 50 MB each. SVG, HTML and other script-bearing formats are refused outright rather than sanitised, because a file that can execute code has no business being re-encoded — and an upload field that accepts one is a security hole rather than a feature. Output is written as JPEG, matching the format the destination expects. Several files can be queued where the workbench supports it. Batch, page and memory limits apply; check every output.

The browser first tries its native decoder because Safari reads HEIC directly. Other browsers fall back to libheif compiled to WebAssembly, loaded dynamically only when a HEIC file is detected by its ISO-BMFF brand rather than its filename. The decoded RGBA pixels are orientation-corrected where metadata is available, then encoded with MozJPEG at conversion quality. Re-encoding removes the original HEIC metadata rather than copying location or device identifiers into the JPG. Each format has its own decoder and encoder path. JPEG, PNG, WebP and AVIF are handled by WebAssembly codecs compiled from the reference libraries, so the same quality decisions apply as in a desktop tool. Transparency is preserved for PNG and WebP, and composited onto white for JPEG, which has no alpha channel — the opposite behaviour to naïve converters that leave transparent regions black. Repeated conversion between lossy formats is discouraged in the interface, because each pass costs a little quality. HEIC support is loaded on demand because the decoder is large and most visitors never need it. Detection uses the ISO-BMFF brand in the file header rather than trusting a filename, and output is freshly encoded so stale metadata does not silently travel into the converted photograph.