ImageGarageiPhones often save photos as HEIC. Many job portals, Windows PCs, and older printers still expect JPG. You do not need iCloud or a desktop converter for a handful of files.
Steps
Open Image Converter, choose JPG as the output, and drop the .heic or .heif file. ImageGarage decodes it locally (this can take a few seconds on a large photo), fills transparent pixels with white, and exports JPEG. Download the result. For several files, use Download all as a zip.
If it fails
Very large HEIC files can hit the 50 MB or 50 megapixel safety limit, or time out after 60 seconds. Try one file at a time. Live Photos are a still plus a video; this tool only converts the still image. Burst or ProRAW variants may not decode in every browser.
Quality
Use the quality slider if the JPG is still too big for an upload form. 80–90% is the usual range. The original HEIC never leaves your device.
Keep the original
JPG is a separate, lossy copy designed for compatibility. Keep the original HEIC when you may want to edit or share the full-quality photo later.