You don't need to buy "PC cleaner" or "driver updater" software. Most of them do little good, and some are harmful. The tools below are free and trusted. Only download them from the official sites listed. Search results and ads often lead to look-alike sites that bundle junk or malware.

Built into Windows (nothing to download)

Tool	What it does	How to open it	Chapters
	Shows what's using the PC, and controls startup apps	Ctrl + Shift + Esc	1, 2, 13
Windows Security (Microsoft Defender)	Antivirus, including the Offline scan	, type Windows Security	1, 13
	Microsoft's automatic troubleshooters	Start button, type Get Help	2, 9, 10
Windows Backup	Backs up files, apps and settings to OneDrive	> Accounts > Windows backup	15
File History	Backs up files to an external drive	> System and Security > File History	15
System Restore	Rolls the PC back to an earlier date	Start button, type rstrui	7
Reliability Monitor	Shows a timeline of crashes and errors	Start button, type reliability	3, 14
Windows Memory Diagnostic	Tests the RAM	Start button, type Windows Memory Diagnostic	3

Free downloads from Microsoft

Tool	What it does	Get it from
Microsoft PC Manager	One-click cleanup, startup and storage tools	Microsoft Store (search "PC Manager")
PC Health Check	Checks whether a PC can run Windows 11	microsoft.com (search "PC Health Check")
Microsoft Safety Scanner	A one-time second-opinion virus scan	learn.microsoft.com (search "Microsoft Safety Scanner")
Windows 11 Installation Assistant and Media Creation Tool	Upgrade, or make a USB stick to reinstall Windows	microsoft.com/software-download

Your PC maker's support app

These find the right drivers and BIOS updates for your exact model, and run hardware tests. Many PCs already have one installed.

Brand	App	Get it from
Dell	SupportAssist	dell.com/support
HP	HP Support Assistant	support.hp.com
Lenovo	Lenovo Vantage	Microsoft Store or support.lenovo.com
ASUS	MyASUS	Microsoft Store or asus.com/support
Acer	Acer Care Center	acer.com/support

Trusted extras

Tool	What it does	Get it from
Malwarebytes Free	A second-opinion malware scanner ()	malwarebytes.com
CrystalDiskInfo	Shows whether the hard drive or SSD is healthy: "Good", "Caution" or "Bad"	crystalmark.info
Ninite	Installs common free apps (browsers, 7-Zip, VLC) with no toolbars or junk	ninite.com

Tools to avoid

Registry cleaners. They rarely help, and can break Windows.
"Driver updater" programs. Use Windows Update and your PC maker's app instead.
Anything a pop-up, cold caller or stranger asks you to install.
A second full antivirus alongside Microsoft Defender. Two antivirus programs fight each other and slow the PC down.