SageThumbs 2K is a modern, crash-isolated Windows 11 shell extension written in Rust that rebuilds the classic SageThumbs. It gives File Explorer thumbnails for 313 file types Windows can't preview on its own — camera RAW, HEIC/AVIF, Photoshop, DjVu, ebooks and comics, video frames, 3D-print files and a long tail of obscure formats — plus a right-click image toolkit (convert, resize, rotate, OCR, color picker, metadata strip, combine-to-PDF/CBZ) and a console/AI CLI. Free for personal use.
README
SageThumbs 2K
Thumbnails for everything Windows won't show you.
A modern, crash-isolated Rust shell extension for Windows 11 — the clean-room revival of the legendary (but decade-abandoned) SageThumbs.
🖼️ Explorer thumbnails for 316 file types it ignores — camera RAW, Photoshop, HEIC/AVIF, video (MKV, WebM, MP4, MOV…), JPEG-XR, MS Office, DjVu, ebooks & comics, 3D-print files, and the obscure long tail.
🛡️ A corrupt or malicious file can't crash Explorer — runs out-of-process, panic-guarded, with a sandboxed decoder.
⚡ Fast even on big files — camera RAW thumbnails from its embedded preview instead of a slow demosaic (3–13× quicker), and no format is allowed to hang a folder.
🧰 Right-click toolkit: convert, resize, lossless rotate, combine-to-PDF/CBZ, system-wide eyedropper, OCR, and more — all non-destructive, and multi-file jobs run in parallel across every core.
🎛️ Make the menu yours — drag-reorder (and show/hide) every right-click entry and its dividers; the context menu mirrors your layout exactly.
🎨 Redesigned Settings — a Win11-style category nav rail with toggle switches, system-following dark mode, 36 languages.
🦀 100% clean-room Rust, free for personal use (PolyForm Noncommercial) — no GFL, no spyware, no personal data.
> I'm a huge fan of SageThumbs. There are 4 things I always install on a new build, Chrome, XnShell, Everything and SageThumbs. Having noticed multiple system crashes from SageThumbs recently and no update in almost a decade, I decided it was time to right this injustice...
>
> After about a week, and an embarrassing amount of tokens, we now have a ground-up, rust native, alternative that now supports 316 formats, has no external dependencies, extensive red teaming, obsessively optimized for speed and install size, dozens of iterations through UI/UX for simplicity, menu editors, a color picker, screenshot tool, etc.
>
> Please tell your friends, star the repo and if you find anything broken, please let me know.
The story
The original SageThumbs was a Windows legend — it made Explorer show thumbnails for hundreds of formats nothing else could. Then it stopped: no updates since ~2017, built on the proprietary, frozen GFL library.
SageThumbs 2K rebuilds it from scratch in safe Rust — a maintained decode pipeline, real crash isolation, and a native Windows 11 look — while keeping the one thing that made it great: thumbnails for everything.
✨ Features
🖼️ 316 formats
Camera RAW (Canon/Nikon/Sony/Fuji/…), PSD, GIMP XCF, DICOM, OpenEXR, FITS, HEIC/AVIF, JPEG-2000/XL/XR, Targa, SGI, and more
📚 Ebooks & comics
EPUB, MOBI/AZW (Kindle), FB2, CBZ/CB7/CBR/CBT — real covers in Explorer (a native-Rust DarkThumbs port)
Pure-Rust, zero-GPL decode via djvu-rs — scanned books show their text
🔊 Docs & audio
PDF first page, Microsoft Office (Word/Excel/PowerPoint) & OpenDocument, and album art for MP3/FLAC/Ogg/Opus/M4A/WMA/DSF (DSD)/… (WMA/ASF and DSD/.dsf via hand-rolled parsers — lofty can't read either)
Multi-file Convert / Resize / Rotate / Strip and Combine-to-PDF fan out across all CPU cores (6–15× faster) — a tiny dependency-free scoped thread pool, no rayon bloat in the shell DLL
🎛️ Make the menu yours
The Settings "Menu items" list lets you drag-reorder every right-click entry and its group dividers — the menu mirrors your layout exactly (WYSIWYG). Tick items off to hide them, or hit Reset order for the default
🤖 CLI + MCP server
st2k.exe — thumbnail · convert · batch · rotate · ocr · pdf · … as a scriptable/AI-agent toolbox (st2k --mcp); batch parallel-processes whole folders in one process. The MCP server adds view (decode any of the 316 formats to a PNG block so an AI agent can see the file) and compress tools
📇 Details pane & columns
An IPropertyStore handler surfaces image dimensions, EXIF camera info and audio tags in Explorer's Details pane, hover tooltips, and sortable/groupable columns — for the 300+ formats Windows can't read itself. Read-only and panic-isolated, like the thumbnailer
🎨 Colour management
Embedded ICC profiles and wide-gamut images (Display P3 / Adobe RGB) render in correct sRGB instead of over-saturated; AVIF/HEIC read their colr box (incl. the iPhone-HEIC CICP Display-P3 signal), and CMYK JPEGs are colour-managed through their embedded profile — pure-Rust, no C deps
🔧 Repair file associations
One button in Settings ▸ Diagnostics re-registers SageThumbs for every enabled format when another app has hijacked the thumbnails, then clears the thumbnail cache
Redesigned Settings — a Win11-style category nav rail (General · File types · Ebook/comic · Right-click menu · Screenshots · Quick action · Advanced) with toggle switches, Common-Controls v6, system-following dark mode, 36 languages
🔍 True transparency
Real premultiplied-ARGB alpha — no more gray checkerboard behind transparent PNGs
⭐ Like it? Help it grow
Built in the open by one person, free for personal use — no ads, no tracking, no paywall. If SageThumbs 2K earns a spot on your "install on every new PC" list, a few seconds of support goes a long way:
⭐ Star the repo — the single biggest signal that this is worth maintaining.
Full bundles a hardened ImageMagick → all 316 formats.
Compact skips ImageMagick → the pure-Rust + OS-codec formats only.
> The installer registers a classic shell extension via regsvr32 and trusts a self-signed cert for the Win11 modern menu. It's a classic extension by design — not an MSIX sandbox — because it spawns ImageMagick as a subprocess.
> First run / SmartScreen: SageThumbs 2K is open-source indie software, and the installer isn't signed with a (paid) certificate — so Windows may show a blue "Windows protected your PC" screen. That's expected for unsigned indie apps: click More info → Run anyway. Every line of the code is right here for you to inspect.
🦀 How it works
IThumbnailProvider → runs in Explorer's isolated dllhost surrogate
│ (first tier that decodes wins; SVG detected up front → resvg)
image crate → WIC (OS codecs) → ImageMagick (sandboxed child) → headerless-Targa
(safe Rust) HEIC/AVIF/RAW the obscure long tail fallback
│
▼ premultiplied-BGRA top-down DIB → Explorer (real alpha)
One DLL exposes three COM coclasses: the thumbnail provider, the modern IExplorerCommand menu, and a classic IContextMenu fallback. Settings live in HKCU\Software\SageThumbs2K.
🛠 Built like it matters
Most thumbnail handlers are a weekend hack. This one's been put through the wringer:
Crash-proof by design — a malformed file can't take down Explorer.
Zero runtime dependencies, pure memory-safe Rust core, installs clean every time.
Zero-warning linting, supply-chain audits, fuzzing, Miri, and a full test + render-regression suite gate every release.
Hardened against hostile input and scanned through VirusTotal each release.
Color-managed (ICC/wide-gamut → sRGB) and obsessively tuned for speed, size, and a native feel.
🗂 Supported formats
316 extensions — Image 188 · RAW 34 · Ebook/comics 12 · Document 42 · Audio 18 · Video 22
Video — mkv/webm, mp4/m4v/mov, avi, wmv, flv, mpg/mpeg, 3gp/3g2, ts/m2ts/mts, ogv, divx, … — a representative frame (~30% in) via the OS Media Foundation codecs
(Plain PostScript and font-only ImageMagick coders are excluded for safety; PDF uses the in-box OS renderer. Video frames come from Windows' own Media Foundation codecs — formats Windows has no codec for, e.g. FLV or MPEG-1/2 without the optional pack, keep their default icon.)
🔧 Build from source
Requires the MSVC Rust toolchain, VS Build Tools (Desktop C++), and — for the installer — Inno Setup.
cargo build --release # sagethumbs2k.dll + sagethumbs2k-app.exe (installs as SageThumbs2K.exe) + st2k.exe
.\scripts\build-release.ps1 # full pipeline → dist\SageThumbs2K-Setup-.exe
SageThumbs 2K is a clean-room rewrite — not a derivative of the GPLv2 C++ original, and it uses no GFL. Every decoder is pure-Rust or an OS codec (RAR/CBR comics use the pure-Rust rars crate — no proprietary UnRAR), so the project's own code is entirely original and its dependencies are permissively licensed — which is what lets us license it as we choose. The optional bundled ImageMagick (for the exotic long tail) ships under its own permissive license and runs only as a sandboxed subprocess.
🙏 Credits
A from-scratch successor to Nikolay Raspopov's original SageThumbs (2004–2017, GPLv2, now unmaintained) — rebuilt clean-room in Rust, with our thanks for the classic that inspired it. Built on image-rs, resvg, windows-rs, djvu-rs, and ImageMagick.
With thanks to the projects that shaped specific features:
DarkThumbs — the model for the ebook & comic cover thumbnails (EPUB / MOBI / FB2 / CBZ…).
Flameshot — inspiration for the screenshot capture + annotation flow.
XnShell / XnView — inspiration for the right-click image toolkit and shell-menu UX.
Calibre — reference for ebook formats and cover extraction.
Made with 🦀 for people who have too many weird files.
