Some antivirus software programs that have a free trial are Norton Security, Malwarebytes and Avast. These free trials range from a week to a month.
Norton Security is one of the top security programs, not only providing antivirus software but other security features as well. There are free trials available for multiple programs by Norton, including Norton Security Deluxe, Norton Security Premium and Norton Mobile Security.
Malwarebytes provides excellent anti-malware protection for computers and mobile devices. There is a 14-day free trial offered for all new customers.
Avast offers a 30-day free trial of their Avast Premier program. Avast also provides a free version of their software that never costs anything.