A cleaner, faster Windows.
Clean up, harden privacy, and tune Windows 11 — 100% free, no payment required. Each tweak states what it changes and how it is undone.
Download for Windows — free, no account required.
Everything you need to tune Windows
Cleanup, tweaks, and restore points in one Windows app.
System cleanup
Find junk and temp files, then reclaim disk space with guided scans.
App & tweak modules
Apply proven Windows tweaks per category — CPU, GPU, network, privacy, and popular apps.
Privacy & telemetry
Turn off noisy Windows telemetry and background data collection where it makes sense.
Restore points
Create checkpoints before changes so you can roll back if something feels off.
Three steps. You stay in control.
From download to a tuned system — you choose what changes.
Install
Download from this page and install OSSI Optimizer on your PC.
Scan
Run a system scan to see what can be cleaned up and which tweaks fit your hardware.
Apply
Pick what to enable, create a restore point, then apply.
Guides
- NVIDIA clean install with NVCleanstall — Step-by-step NVIDIA driver install with NVCleanstall: latest Game Ready package, unattended install, clean install, telemetry off, and verification.
- Best NVIDIA driver choice — When to update NVIDIA drivers, which versions to trust, what to avoid, and how to downgrade safely with DDU.
- Clean Windows install from USB — Fresh Windows 10/11 install: backup, USB media, wipe partitions, offline setup, driver order, and gaming tuning.
- FPS dropped over time — Why a PC felt faster when new: thermals, startup bloat, drivers, overlays, power limits, and when to reinstall Windows.
Install warnings & safety
Windows may warn on unsigned installers. Here is what that means and what to do.
Why does Windows say the app is dangerous?
Windows warns because the installer isn't signed with a paid code-signing certificate yet. That doesn't make the app more unsafe — it just means Windows doesn't recognize the publisher. When we sign releases, those warnings go away. Only download from optimizer.ossidev.dk.
What do I do when I see “Windows protected your PC”?
Click More info, then Run anyway. If you do not see Run anyway, right-click the installer → Properties → check Unblock on the General tab, then run it again.
Smart App Control blocks the installer
Smart App Control often blocks unsigned installers — same reason as SmartScreen, not because the file is malicious. There is no per-app allowlist. To install now: open Windows Security → App & browser control → turn off Smart App Control temporarily, install OSSI Optimizer, then turn it back on. Signed releases will avoid this once we have a certificate.
VirusTotal shows a trojan — is it safe?
Antivirus tools often flag apps that change system settings and run admin commands. Optimizer does that on purpose — tweaks, cleanup, restore points. A detection here is usually a false positive, not a confirmed trojan. We can't avoid some scanners flagging that behavior.