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ImageGlass is a free open-source image viewer by Duong Dieu Phap that opens HEIC, RAW, WebP, JPEG XL and around ninety other formats with no extra codecs installed, alongside an optional paid Pro tier most people will not need.
Windows opens a JPEG and gives up on most of what a modern phone or camera produces.
ImageGlass opens all of it, and it does so without installing a single extra codec.
That is the whole appeal, and it is why it has been downloaded seven million times since 2010.
What It Opens With Nothing Else Installed
The viewer ships its own decoders, so around ninety formats work the moment you install it.
That covers the everyday ones - JPEG, PNG, GIF, BMP, TIFF - and, more usefully, the ones Windows still stumbles on. HEIC from an iPhone, camera RAW from Canon, Nikon and Sony, WebP, JPEG XL, SVG, PSD and HDR images all open directly.
You do not need the Microsoft codec extensions for this
The HEIF, WebP and RAW extensions from the Microsoft Store are decoders for Windows itself - they are what make File Explorer show thumbnails and let Photos open the file. ImageGlass bypasses Windows entirely and uses its own, so installing them changes nothing inside ImageGlass.
They are still worth having, for a different reason - Windows keeps showing blank icons in File Explorer until it can decode these formats itself.
The HEIF Image Extensions and the WebP Image Extensions cover HEIC and WebP thumbnails.
The Raw Image Extension does the same for camera RAW files.
For camera RAW specifically, our guide on which codec or app you actually need for Nikon RAW works through the difference between viewing a file and editing it.
Classic or Pro?
ImageGlass split into two editions with version 10, and the split is friendlier than most.
Classic is the open-source edition under GPLv3. It is a complete viewer - every format, every theme, the plugin system, colour management, the built-in colour picker, crop and resize tools. Nothing is time-limited and nothing nags.
Pro adds a small set of things aimed at professional and managed use: free and margin panning, a dedicated HDR tone mapper, a file watcher that reacts the instant a file changes on disk, and two administrator controls that lock settings or features across a deployment.
Read that list and the honest conclusion is that most people are done at Classic. Pro earns its money in an HDR workflow or on a fleet of managed machines, and nowhere much in between.
It Runs on macOS and Linux Now
Version 10 was rebuilt on a shared cross-platform codebase, so the same viewer runs on Windows, macOS and Linux.
That is new, and it matters if you have been keeping a different viewer on each machine. The build on this page is the Windows one.
Speed, and Where It Comes From
The performance claim is not marketing. ImageGlass uses asynchronous file reading, predictive caching and hardware acceleration, which is why scrolling a folder of large photographs stays responsive instead of stuttering.
Navigation is arrow keys through a folder, mouse wheel to zoom, and a thumbnail gallery along one edge so you can jump anywhere in the folder without going back to Explorer.
It also handles large images without the memory problems that make lighter viewers give up, and it steps through animated frames properly rather than playing them and hoping.
Making It Yours
Themes, language packs, toolbar position, gallery layout, mouse actions and hotkeys are all configurable, and the hotkeys are fully remappable rather than a fixed list.
There is a published SDK, so plugins and native codec extensions are a supported route rather than a hack. Community themes and plugins are distributed from the project site.
Colour profiles are respected, and EXIF data is there when you want it. If you only need to read the metadata out of one file without installing anything, that works in a browser.
ImageGlass or One of the Other Free Viewers?
The Image Viewers category on this site is unusually crowded, and the choice comes down to what you want the viewer to also do.
| Viewer | Its strength | Pick it when |
|---|---|---|
| ImageGlass | Modern formats with no setup, heavy customisation | You want HEIC, RAW and JXL to just open |
| IrfanView | Editing and batch conversion built in | Viewing is only half of what you need |
| XnView | Over 700 formats, including obscure ones | You hit files nothing else recognises |
| FastStone Image Viewer | Batch processing and a real editor | You process photos in bulk |
| JPEGView | Tiny, and starts before you finish clicking | You want the absolute minimum |
| PicView | Similar philosophy, also cross-platform | You want a second opinion on the same idea |
Fly Photos is the one to look at if what you actually miss is the old Picasa viewer, and WildBit Viewer if slideshows are the point.
The rest are in the Image Viewers section.
Who Should Look Elsewhere
The tell is whether you want to change the picture or just look at it.
ImageGlass crops, resizes and picks colours, and stops there. If you need levels, layers, red-eye removal or batch watermarking, a viewer with an editor bolted on will serve you better.
If you would rather not install anything at all and Windows already opens what you have, Microsoft Photos plus the right extension is the lighter answer. And if a single stubborn HEIC file is the entire problem, you can open it in a browser and skip the software question.
Quick questions
Is ImageGlass free, or is the free version cut down?
The Classic edition is free and open source under GPLv3, and it is a complete viewer with no time limit and no format restrictions. Pro is a separate paid tier for HDR tone mapping, file watching and administrator controls.
Do I need to install codecs for HEIC or RAW?
No. ImageGlass carries its own decoders and opens both straight away. The Microsoft Store extensions are for File Explorer thumbnails and the Photos app, not for ImageGlass.
Does it run on Mac or Linux?
Yes, since version 10, which was rebuilt on a shared cross-platform codebase. The download on this page is the Windows build.
Can it edit photos?
Only lightly. There is a colour picker, a crop tool and a resize tool. For anything more, IrfanView or FastStone Image Viewer include real editors.
Will it open JPEG XL and AVIF?
JPEG XL is supported directly and is one of the formats the project highlights. Format coverage runs to roughly ninety types and is extendable through native codec plugins built on the project SDK.
How do I make it the default image viewer?
Through Windows rather than through the app - open Settings, then Apps, then Default apps, and set ImageGlass per file type. Windows 11 deliberately makes this per-extension rather than all at once.
Download ImageGlass 10.0.6.906 and see how it handles your photo folder, or tell us how you got on - this page has no reviews yet.
