"Let's build the fastest image viewer in the world." — and that's exactly what we did.
BoltView is a Windows image viewer built around one thing only: speed. It's faster than any image viewer out there.
Most viewers aren't slow because of the time it takes to read a file — they're slow because of the time it takes to decode the compression in JPEG and PNG files.
BoltView was redesigned from scratch on one principle: "never decode at the moment you need to display." That erased the wait when you flip through photos.
Click, and it's already on screen. The next photo shows up instantly.
▶ Why it's the fastest
· Prefetch decoding: the images before and after the one you're viewing are decoded in the background and kept ready in memory. ← next/previous is instant
· GPU rendering (Direct2D): zoom, pan and rotation are handled by your graphics card, so every screen transition finishes in a single frame.
· LRU memory cache: an image you've already seen is never decoded again.
· libjpeg-turbo acceleration: decodes JPEG 2-4x faster with SIMD.
· Parallel thumbnails + OS cache reuse: gallery thumbnails fill in the blink of an eye.
▶ Find a photo by name
· Initial-consonant search: it matches file names, and initials are enough — type ㄱㅎㅍ and 김학필.jpg comes up.
· It matches exactly what you typed: nothing similar-looking gets slipped in, so everything in the list is what you were looking for. v2.0.1 tightened that precision further.
· Live results while you type: results update as you type — no need to press Enter or finish the word (Korean results update mid-composition, before a syllable is even complete).
· A search box you can actually edit: drag to select a range and clear it in one go, instead of holding backspace.
· Switch the scope: this folder only, or the whole PC — you pick inside the app.
· Whole-PC search borrows FastFind's index: BoltView builds no index of its own. If FastFind — a file search tool by the same developer — is installed, BoltView only reads its index; the viewer never crawls your disks in the background. Without it, the search stays inside the folder you're looking at.
· For reference, FastFind's own measurements: 5.3ms for a first query (Everything: 82.8ms), 43x faster when you keep typing letter by letter, 10ms for a whole-PC search over a 3.2M-file index, 4.66M entries indexed in 65.9MB, index startup under a second.
▶ Documents and archives
· BoltView isn't only for photos. PDFs are not handed off to Windows Preview — BoltView draws them itself, through the very same pipeline as your photos.
· Opens without Office installed: PDF, XLSX, CSV, plain text, JSON.
· Needs the matching program: DOCX, PPTX, Hangul (HWP), legacy XLS — these go through Windows Preview, so the program that opens them has to be on the PC.
· ZIP: opened as-is without unpacking, and paged through one page at a time.
▶ Key features
· Gallery (browse) start screen: folder tree on the left + thumbnail grid, pinned favorites and recent folders, multi-select with drag / Ctrl / Shift
· Find photos by name: file-name search with initial-consonant matching, narrowing as you type. Scope widens to the whole PC when FastFind is installed
· Documents and archives: PDF drawn by BoltView itself; XLSX, CSV, text and JSON open without Office; ZIP paged through without unpacking
· Viewing: fit / 100% / fill, cursor-anchored wheel zoom, rotate/flip, automatic EXIF rotation, animated GIF
· File actions: delete to Recycle Bin, copy, save as (lossless JPEG rotation), set as desktop wallpaper, open file location
· 4 themes: Dark / Light / Black (OLED) / Night (sepia) + auto match system
· 4 languages: Korean / English / Japanese / Chinese (auto-detects system language)
· Slideshow, filmstrip, info panel, full keyboard shortcuts, DPI-aware
· Automatic updates: checks once a day whether a new build exists — downloading is your call
▶ Automatic updates
· From v2.0.1 on, BoltView checks for a new build by itself. It only checks.
· 20 seconds after the window opens, once a day, it looks at the version number and nothing else.
· If there's a new build it shows a notice at the bottom of the screen. Nothing is downloaded until you click it.
· A downloaded file is verified against its SHA-256 and swapped in only if it matches, then BoltView restarts itself. If the hash doesn't match, the file is discarded.
· Nothing is sent to the server. It only fetches.
· You can turn it off under [Settings > Updates]. With it off, the networking DLL is never even loaded.
▶ What it's built with
· C++17 / Win32 API (native, lightweight)
· Direct2D (GPU rendering) · WIC (decoding) · DirectWrite (text)
· libjpeg-turbo (JPEG acceleration)
· No external runtime to install, single executable
· More about BoltView on the official site.
▶ Install / Download
· Installer: BoltView-Setup.exe (auto file association + shortcuts)
· Portable: BoltView-portable.zip (unzip and run BoltView.exe)
· Supported: Windows 10 / 11 (64-bit)
▶ Essential shortcuts
←/→ previous·next · wheel zoom · F fit to screen · F11 fullscreen · Space next · Del delete · Esc back to gallery/close
Frequently Asked Questions
Is it really the fastest?
Yes, it's the fastest image viewer available today. With prefetch decoding + GPU rendering + LRU cache + libjpeg-turbo combined, cached photos switch within a single frame (about 16ms).
Is it free?
Completely free. A no-install portable version is available too.
What formats does it support?
Images: JPEG, PNG, GIF (animated), BMP, WebP, TIFF, ICO, HEIC and more (HEIC requires the Windows codec). Documents: PDF, XLSX, CSV, plain text and JSON open without Office installed. DOCX, PPTX, Hangul (HWP) and legacy XLS go through Windows Preview, so the program that opens them has to be on the PC. ZIP is opened without unpacking and paged through one page at a time.
I can't remember which folder the photo is in. Can I still find it?
Just type part of the name. Initial-consonant search works too — type ㄱㅎㅍ and 김학필.jpg comes up. It matches exactly what you typed and slips in nothing that merely looks similar, so everything in the list is what you were after.
Do I need FastFind for whole-PC search?
The whole-PC scope needs FastFind's index. BoltView builds no index of its own — it only reads FastFind's. Without FastFind, the search stays inside the folder you're currently viewing.
How do I update?
v2.0.1 added automatic updates. 20 seconds after the window opens, once a day, BoltView checks the version number and shows a notice at the bottom of the screen if a new build exists. Nothing is downloaded until you click it, and a downloaded file is applied only when its SHA-256 matches. You can turn it off under [Settings > Updates].
Are PDFs fast too?
PDFs aren't handed off to Windows Preview — BoltView draws them itself, through the same pipeline as photos. They open and page the way photos do.
Can I set it as my default image viewer?
Yes, from the app under [Settings > System > Set as default image viewer].