Use the Photos app on iPhone, iPad, or Mac
Open it with the Files app on iPhone or iPad
Use Preview on Mac
Open it in Windows Photos if HEIC support is installed
Install the HEIF Image Extensions on Windows
Use a third-party image viewer that supports HEIC
Convert the HEIC file to JPG or PNG
Upload it to an online HEIC viewer or converter
Open it in Google Photos
Open it in Adobe Lightroom or Photoshop with HEIC support