There are pentest tools, such as a website vulnerability scanner, that can help you figure out how to pentest your website. However, online web pentesting may have limitations in what issues it can discover or resolve. If you want a comprehensive pentest, you should hire an expert, whether it’s a freelance pentester or a company dedicated to testing web vulnerability. They will need to seek approval from whoever owns the network, service, or application before they can conduct a pentest.