v1.3.0

• 4K images. Alongside the videos, Win4KSS can now show about 4,500 free high-resolution images: landscapes and nature photography, space (Hubble, Webb, ESO, NASA), fine art (Art Institute of Chicago, Rijksmuseum), and abstract and geometric art.
• New Video / Image filter in the clip browser. Image sources are opt-in: add the ones you like to your rotation from the clip browser.
• Each image shows for 15 seconds with a slow pan and zoom (both adjustable in Settings → Images), with a small credit to the photographer or source in the corner.

v1.2.6

• Faster hotkey. Ctrl+Alt+S now starts the screen saver about as quickly as the Start now button.
• The hotkey no longer needs a shortcut. It keeps working if you remove the Desktop or Start Menu shortcut. Change it or turn it off under Settings > Start now; changes apply at once.
• Selection follows your filters. Changing a filter or search drops hidden clips from the selection, so bulk actions only affect the clips you can see.
• Tidier toolbar. The selection count and the rotation and offline buttons now sit in the toolbar at the top, next to search and sort.

v1.2.5

• Updates no longer ask for permission. Win4KSS now installs into your user account, so updating from the app needs no admin rights: no Windows prompt, no installer pages. It closes the clip browser for a few seconds and reopens it on the new version.
  • Updating to 1.2.5 from an older version asks once more, to move Win4KSS's Apps & features entry to your user account and refresh its entry in Windows' screen saver list. After that, updates are prompt-free.
• Play now. Open any clip in the clip browser and click ▶ Play now: the screen saver starts right away with that clip, even if it isn't in your rotation, then carries on through your rotation.

v1.2.4

• No more same few clips every time. The screen saver kept opening with one of the same handful of clips, the few Apple labels "Day" or "Night", because it put them first in every session. Now every clip in your rotation has an equal chance to open; time of day only pushes clips meant for the other half of the day to the back.
• An empty rotation plays Apple's aerials, not just whatever happens to be cached.
• Quieter updates. Installing an update from the app now shows just the Windows permission prompt and a progress bar, then reopens the clip browser. No installer pages to click through.

v1.2.3

• Every clip in your rotation plays, not just the cached ones. Before, a few streaming failures in a row made the screen saver stick to the clips already on disk for the rest of the session, and stop downloading new ones. Now it only leans on cached clips for a few minutes, keeps downloading upcoming clips in the background, and then goes back to the full rotation.

v1.2.2

Fixes for a fresh install on a new PC.

• The screen saver plays on a new PC. The copy of Win4KSS that Windows runs from System32 now hands off to the installed app, so a firewall that allowed Win4KSS can no longer block the screen saver's streaming. Before this, a new PC could show only a black screen.
• Start now (and Ctrl+Alt+S) always starts the screen saver, even when Win4KSS isn't set as the Windows screen saver. If "On resume, display logon screen" is on, it still locks when you come back.
• No more silent black screen. If no video can load, the screen saver says so.
• Hover previews work out of the box. ffmpeg now ships with Win4KSS.
• Nothing to install by hand. If the .NET 10 Desktop Runtime or the WebView2 Runtime is missing, Setup downloads and installs it.
• The app icon shows in Start, search, and Settings → Apps.

v1.2.1

Test release for the auto-updater: a small visible change (a tagline under the version line in Settings → About) so an installed v1.2.0 can confirm its auto-update check, download, verification, and install actually work end to end.

Also: README rewritten with a banner and cleaner formatting.

No other functional changes.

Win4KSS v1.2.0

What changed

• Automatic updates. The clip browser (/c) now checks for new releases on its own (once every 24 hours, or anytime via a "Check now" button in Settings → About), shows what's new, and lets you install with one click. Downloads are verified — size and SHA-256 against a checksum published with the release itself, never just GitHub's own metadata — before anything runs; a failed check never shows a popup or interrupts anything, and it never runs during the screensaver itself. Can be turned off in Settings → About if you'd rather update manually.
• Builds now come with a published checksum. Every release from here on includes a .sha256 file alongside the installer — this is what the new auto-updater checks against, and you can verify it yourself too (CertUtil -hashfile Win4KSS-Setup-1.2.0.exe SHA256 on Windows, or sha256sum -c).

One thing worth knowing

This is the last manual update before updates become automatic. v1.1.1 (and everything before it) has no update-checking code at all, so if you're on an older version, this is the one you need to grab by hand. From here on, the app will tell you when something new is out.

Install

Download Win4KSS-Setup-1.2.0.exe below. SmartScreen will likely warn since it's unsigned (expected, click through it).

Full docs: README.md · Troubleshooting · Signing policy

Unofficial, not affiliated with Apple.

Win4KSS v1.1.1

v1.1.0 is broken — do not use it. It crashed on literally every install attempt with "Internal error: An attempt was made to expand the 'app' constant before it was initialized," 100% reproducible, before any files were even copied. This release fixes that and adds one more safety check.

What changed since v1.1.0

• Fixed the install-breaking crash. A scripting bug ({app} used before Inno Setup had resolved it — my mistake, caught by real-world testing, not by me beforehand).
• Added a .NET Desktop Runtime check. This app needs the .NET Desktop Runtime (x64) already on the machine — a bare Windows 10 install typically doesn't have it (Windows 11 doesn't bundle it either). The installer now checks for it up front and tells you clearly, with a download link, instead of installing something that would silently fail to launch.

v1.1.0's other changes (the clip browser, settings export/import, the packaging rework with the restored Screen Saver Settings dropdown) are unchanged — see that release's notes for the full list.

Install

Download Win4KSS-Setup-1.1.1.exe below. SmartScreen will likely warn since it's unsigned (expected). If this PC doesn't have the .NET Desktop Runtime, the installer will tell you and link straight to it.

Full docs: README.md · Troubleshooting · Third-party notices

Unofficial, not affiliated with Apple.

Win4KSS v1.1.0 — BROKEN, see v1.1.1

Warning

This release is broken — do not install it. It crashes on every single install attempt with "Internal error: An attempt was made to expand the 'app' constant before it was initialized," before any files are even copied. Use v1.1.1 instead, which fixes this and adds a .NET Desktop Runtime check.

Second release. Three real changes since v1.0.0.

What changed

• The clip browser. /c (or the Start Menu shortcut) now opens a full clip-browsing UI: tag filters, sortable thumbnail grid, hover previews, a live detail pane, and per-clip "in rotation" / "keep offline" controls across ~1,500 clips from Apple, the Internet Archive, NASA and a few vendor feeds. The old plain settings dialog is gone.
• Settings export/import. Settings → About → "Backup / move to another machine" writes a readable *.win4kss.json file (your rotation, pins, playback/cache preferences — not the video cache itself) that imports cleanly on another install. Also available headless: Win4KSS.exe --export-settings <file> / --import-settings <file>.
• Packaging changed to fix an antivirus false positive — without losing the Screen Saver Settings dropdown. v1.0.0 bundled its native DLLs (libmpv-2.dll, the WebView2 loader) inside a single self-extracting exe — a pattern some antivirus heuristics (confirmed: Bitdefender) flag on sight, since it's structurally how a dropper behaves, regardless of what the code actually does. This build ships those as ordinary loose files next to Win4KSS.exe instead, which removes that pattern. To keep this app listed in Windows' own Screen Saver Settings dropdown (which only ever scans System32 for .scr files) without putting those DLLs in System32 itself — System32 sits on every process's DLL search path, and a name like WebView2Loader.dll is shared across every WebView2 app on the machine, so a copy there could get picked up by unrelated software — the installer now builds a second, separate single-file variant with no native DLLs bundled at all just for that one slot; it finds libmpv/WebView2 in the regular installed copy at startup instead. Verified on a real machine: System32 ends up holding exactly one new file, nothing else.
  • This isn't a guarantee of zero AV flags anywhere. A brand-new, unsigned file still has no download history, and that alone can draw a first-contact flag from one or two engines independent of anything structural. If you hit one, it's worth a false-positive report (see docs/TROUBLESHOOTING.md), and checking virustotal.com against the exact file is the fastest way to see the real multi-engine picture.

Install

Download Win4KSS-Setup-1.1.0.exe below, run it, SmartScreen will likely warn since it's unsigned (expected, click through it). "Make Win4KSS available in Windows' Screen Saver Settings" is checked by default.

Full docs: README.md · Troubleshooting · Third-party notices

Unofficial, not affiliated with Apple. See third-party notices for the GPL libmpv build and the licensing breakdown of the streamed clip catalogue.