Starting with IrfanView 4.40 there is also a 64-bit version available.
Advantages of IrfanView 64-bit over 32-bit version: ◾It can load VERY large files/images (image RAM size over 1.3 GB, for special users) ◾Faster for very large images (25+ Megapixels, loading or image operations) ◾Runs 'only' on a 64-bit Windows (Vista, Win7, Win8, Win10) Advantages of IrfanView 32-bit over 64-bit version: ◾Runs on a 32-bit and 64-bit Windows ◾Loads all files/images for normal needs (max. RAM size is about 1.3 GB) ◾Needs less disc space ◾All PlugIns will work: not all PlugIns are ported (yet) to 64-bit (like OCR) and some 32-bit PlugIns must be still used in the 64-bit version, some with limitations (see the "Plugins32" folder) ◾The Unicode and many Adobe 8BF PlugIns can't work on 64-bit ◾Command line options for scanning (/scan etc.) work only in 32-bit (because no 64-bit TWAIN drivers)
Notes: ◾You can install both versions on the same system, just use different folders. For example: install the 32-bit version in your "Program Files (x86)" folder and the 64-bit version in your "Program Files" folder (install 32-bit PlugIns to IrfanView-32 and 64-bit PlugIns to IrfanView-64, DO NOT mix the PlugIns and IrfanView bit versions) ◾The program name and icon have some extra text in the 64-bit version for better distinguishing