Compare software

Avast Free Antivirus vs Microsoft Defender: catalog facts
Avast Free Antivirus	Microsoft Defender
Freemium The antivirus is free; Avast sells a VPN and other paid products.	Paid Included with a paid Microsoft 365 subscription, with a free trial available.
Windows, macOS, Android	Windows, macOS, Android, iOS
Free antivirus from a large vendor Available for Windows, macOS and Android	Manages security for several family members and devices from one dashboard Dark web monitoring for more than 60 types of personal information
Closed source Promotes paid products from within the free offer	Requires a Microsoft account and a Microsoft 365 subscription Closed source, with protection tied to Microsoft's cloud services
Downloadable app	Downloadable app
Closed source	Closed source
License not stated	License not stated
Not stated if an account is needed	Account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.