This viewer is a free HEIC, HEIF photo viewing online app, which can open and view HEIC/HEIF images.
This app allows you to view and decode directly HEIC images in your browser, and Save as a PNG, JPEG file format. 
HEIC files are supported by Apple Preview and Apple Photos (macOS High Sierra and later), and iOS Photos (iOS 11 and later). 

This HEIC Viewer does not save or share the file you select. It only works locally without going through the server. (HTML5 technology)
You can open an unlimited number of HEIC image files to view from your computer or your Google Drive™.