Avast had more than 435 million monthly active users[2] and the second largest market share among anti-malware application vendors worldwide as of April 2020.

[8] At the institute, Pavel Baudiš discovered the Vienna virus on a floppy disk and developed the first program to remove it.

[9][11] In 1995, Avast employee Ondřej Vlček [cs] wrote the first antivirus program for the Windows 95 operating system.

[8] By 2001, Alwil was experiencing financial difficulties, when it converted to a freemium model, offering a base Avast software product at no cost.

[14] The following December, Avast filed for an initial public offering, but withdrew its application the following July, citing changes in market conditions.

[20] Additionally, Avast's online support forum was compromised in 2014, exposing 400,000 names, passwords and email addresses.

[29] In April 2020, Avast released a new secure, private mobile web browser for Android based on technology acquired from previously unreported acquisition of Tenta, a Seattle-based startup.

In September 2022, the Competition and Markets Authority approved the proposed takeover by NortonLifeLock so allowing the transaction to be completed.

[31][32][33][34][35] Avast develops and markets business and consumer IT security products for servers, desktops, and mobile devices.

[38] Additionally, Avast has developed utility software products to improve battery life on mobile devices, cleanup unnecessary files on a hard drive, find secure wireless networks[39] or create a VPN connection to the internet.

[38] For example, the desktop product will look for vulnerabilities in the wi-fi network and run applications suspect of having malicious software in an isolated sandbox.

[47][48] A review in Tom's Guide says that the free Avast antivirus product has "good protection against malware" and takes up little space on the system.

[50] The review said that the software had good features, protection, configuration and an "excellent interface", but it took up a lot of hard disk space and did not cover mobile devices.

[43] The review highlighted that the software has a small system footprint and has good malware protection, but does not have a quick scan option and lacks many additional features.

[43] In late 2019, Avast browser extensions were found to collect user data, including browsing behavior and history, and send it to a remote server.

In response, Avast announced on January 30, 2020, that it would immediately shut down Jumpshot and cease all operations due to the backlash of its users' data privacy.

[58][59] On the basis of the information revealed, on 11 February 2020 the Czech Office for Personal Data Protection announced that it had initiated a preliminary investigation.