I'm thinking about the security of my online platforms and thought I should do penetration testing, but I don't know where to start. Has anyone used a security testing service? Can you tell me how to choose a reliable company or specialist for this task?

There are several important things to consider when choosing a company for penetration testing. The first is experience and reputation in this area, so that the tester can identify vulnerabilities and offer competent solutions. Also look at what methods they use so that the testing is as in-depth as possible. There is a good resource with information about such services, where you can find out how it happens: https://pharosproduction.com/penetration-testing-services