Avast Free Antivirus vs Microsoft Defender Antivirus Comparison

• Free Antivirus: Free; the mobile apps show third-party ads
• Premium Security for 1 computer and 1 phone, renewal: $77.99 a year, the price the store calls the renewal price
• Premium Security for 1 computer and 1 phone, first year: Intro: $49.08 for the first year
• Premium Security for 10 devices, renewal: $99.99 a year, the price the store calls the renewal price
• Premium Security for 10 devices, first year: Intro: $69.48 for the first year
• Ultimate for 10 devices, renewal: $139.99 a year, the price the store calls the renewal price; $69.48 for the first year

• Included in Windows: Built into Windows; not sold separately

The product privacy notice says the desktop app sends samples of suspicious files and detection metadata to Avast's servers through CommunityIQ, and that it may 'directly analyze and maintain these artifacts in our safe environment'. It also lists the URLs of websites visited, 'malicious and non-malicious', and referrers, kept for 36 months for service provision. The support article says file-sample sharing (CommunityIQ) can be unticked in Settings ▸ General ▸ Personal Privacy. On phones, SMS Guard keeps texts that contain links or come from senders not in your contacts, with personal identifiers removed, for up to five years.

Cloud-delivered protection is on by default. When the app cannot decide about a file on the device, it sends the file's metadata to Microsoft: hashes, file name and size, signer, the process that touched it, the download address and IP, the hashed file path, and the device's OS version, locale and geographical location. If that is not enough, Microsoft can request the file itself. The default setting sends 'safe samples' such as .exe, .dll and .bat files automatically and asks you before sending a file likely to contain personal data. You can switch off sample submission or cloud-delivered protection in Windows Security; Microsoft's documentation says detection metadata is still sent when sample submission is off.

The Gen Digital privacy notice says 'We do not sell your personal data to third parties', but also that 'Where permitted by applicable law, we may share personal data with third parties for advertising purposes' and that data is used 'to serve you with relevant advertising and content, both on our properties and on third-party properties'. The consent policy says free mobile apps show third-party ads from partners such as AdMob, Amazon, Facebook Audience Network and InMobi, with consent asked at installation and a paid ad-free version. The desktop app uses Google Analytics; the phone apps use Google Firebase, AppsFlyer and Singular. In the free desktop version, sharing app-usage data for Avast's own offers is on by default and cannot be switched off.

Microsoft's privacy statement says Defender Antivirus automatically sends reports about suspected malware and unwanted software and may send files for inspection, asking first if a report may contain personal data. Windows required diagnostic data, which includes a Defender health event with a Defender machine ID, is stored with unique identifiers and used to keep Windows secure and to improve Windows. If you turn on the Windows setting Personalized offers, Windows diagnostic data is also used for tips, ads and recommendations. The statement also says Microsoft discloses personal data for digital advertising, and in response to valid legal process from law enforcement and government agencies.

For users in the European Economic Area the controller of personal data is Avast Software s.r.o., Pikrtova 1737/1A, Prague 4, Czech Republic, so EU data protection law applies to it. Avast's parent, Gen Digital Inc., has its privacy team in Tempe, Arizona, and the group's general privacy notice says it may disclose data to public authorities and in legal proceedings. In the US case of 2024 the FTC named Avast Limited, a UK company, and its Czech subsidiary.

Microsoft Corporation, One Microsoft Way, Redmond, Washington, is the data controller; for the European Economic Area, the UK and Switzerland it is Microsoft Ireland Operations Limited in Dublin. Microsoft takes part in the EU–US, UK and Swiss data privacy frameworks.

Avast was founded in Prague in 1988 as Alwil Software. On 12 September 2022 the US company now called Gen Digital, listed on NASDAQ, completed its acquisition of Avast; the Avast website and policies now carry Gen Digital's name.

Microsoft was founded in 1975 and trades on the stock market as MSFT. Its antivirus began in 2009 as Microsoft Security Essentials, became Windows Defender in Windows 8 and 10, and was renamed Microsoft Defender Antivirus in 2020.