Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsYes, you can install Malwarebytes alongside Windows’ built-in antivirus, Microsoft Defender Antivirus, but installation does not mean both are actively protecting you as antivirus engines. Microsoft says a compatible third-party antivirus automatically turns Defender Antivirus off. Check Windows Security’s provider status to see which product Windows recognizes as active.
What happens when you install Malwarebytes?
“Windows Defender” is the familiar name many people use for Microsoft Defender Antivirus, which is managed through the Windows Security app. It is different from the separate Microsoft Defender app included with some Microsoft 365 subscriptions. Microsoft’s overview of Windows Security explains the built-in protections and scan options.
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Malwarebytes says its Windows app is designed to work with other antivirus software. However, Microsoft says a compatible non-Microsoft antivirus program automatically turns Microsoft Defender Antivirus off. In practice, both applications may be installed, but Windows may not use Defender as the active antivirus provider while it recognizes another compatible antivirus. Check Windows’ status rather than assuming both are simultaneously providing active antivirus protection.
How to check which antivirus is active
- Open the Windows Security app.
- Select Virus & threat protection.
- Select Manage providers and review the antivirus provider status shown there.
Microsoft’s Virus & threat protection guide describes this area of Windows Security. Microsoft also says Defender Antivirus should return to active mode automatically after a non-Microsoft antivirus is uninstalled.
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Is Malwarebytes Free enough to use with Defender?
That depends on whether you want occasional, on-demand scans or Malwarebytes’ paid real-time features. Malwarebytes’ Windows feature table, updated September 8, 2026, lists Quick Scan and Custom Scan as free; Threat Scan, Scheduled Scan, and Real-Time Protection are paid.
| Malwarebytes Windows feature | Availability in the table updated September 8, 2026 |
|---|---|
| Quick Scan | Free |
| Custom Scan | Free |
| Threat Scan | Paid |
| Scheduled Scan | Paid |
| Real-Time Protection | Paid |
These are feature-availability details, not evidence that running two active antivirus engines improves protection. Microsoft Defender Antivirus also offers quick, full, custom, and Microsoft Defender Offline scans, as well as scanning a selected file or folder; see Microsoft’s scan guidance.
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- Malwarebytes Premium: Available for Windows, Mac, iOS, Android and Chromebook. 24/7 real-time protection against emerging threats
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Check Windows compatibility before installing
Malwarebytes lists Windows 10 and Windows 11 support, requires S mode to be disabled, and specifies a minimum of 4 GB of memory and 1 GB of disk space at installation. Check the current Malwarebytes system requirements before installing, since requirements may change.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Malwarebytes’ Windows installation guidance describes downloading and installing the app, then activating it with an account, license key, or activation code. Follow the current Windows installation instructions for the applicable setup.
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- AWARD WINNING Antivirus, anti-malware, anti-spyware & more
- 24/7 REAL TIME PROTECTION against emerging malware threats, including ransomware and viruses- without slowing you down
- PROTECTS YOUR DEVICES ON MULTIPLE PLATFORMS: Get cyber protection for your computers, smartphones, or tablets- Compatible with Windows, Mac, Android, iOS devices
- DOWNLOAD AND INSTALL INSTANTLY
- UNMATCHED THREAT DETECTION: We found malware on 40 percent of devices that already had a third-party antivirus installed
What to do if the apps conflict
Malwarebytes lists blocked apps, another antivirus stopping, loss of internet access, and Windows blue-screen errors among possible issues. Its guidance recommends adding each app to the other’s allow list where appropriate. This is troubleshooting advice, not a guarantee that every configuration will work. See Malwarebytes’ allow-list instructions.
For certain network or crash problems, Malwarebytes points to overlapping use of Windows Filtering Platform by web-protection features. Its troubleshooting guidance includes seeking help to disable the other antivirus’s website protection or, if necessary, turning off Malwarebytes Web Protection. Turning off that feature reduces Malwarebytes’ web protection, so treat it as a targeted troubleshooting step rather than a routine setup change. See Malwarebytes’ Windows Filtering Platform guidance.
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- Check Windows Security’s provider status before changing settings.
- If a specific app or connection is blocked, investigate the allow-list guidance for both products.
- If the issue persists or the products prove incompatible on your PC, Malwarebytes recommends uninstalling the other antivirus.
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