Several programming languages are commonly used for creating advanced website functionality. At Seota, we use many different tools, and the list changes frequently, but there have been languages that have stood the test of time.  Generally, the choice of web programming language depends on the specific requirements of the project, the type of website or web application being built, and the experience and preference of the development team. Here are some of the most commonly used programming languages for complex web development projects:

1. JavaScript: JavaScript is a popular programming language for web development, used for both front-end and back-end development. It is used to create dynamic and interactive websites, web applications, and mobile applications.
2. PHP: PHP is a popular server-side scripting language for web development. It is widely used for building dynamic web applications and content management systems (CMS) such as WordPress and Drupal.
3. Python: Python is a high-level programming language commonly used for web development due to its ease of use, simplicity, and flexibility. It is widely used for back-end development, machine learning, and data analytics.
4. Ruby: Ruby is a programming language commonly used for web development, particularly with the Ruby on Rails framework. It is a high-level language that is known for its simplicity and ease of use.
5. Java: Java is a popular programming language for web development, particularly for enterprise-level applications. It is widely used for building complex web applications and e-commerce platforms.
6. C#: C# is a programming language developed by Microsoft and commonly used for web development on the Microsoft .NET framework. It is widely used for building web applications and software for Windows platforms.

Other languages such as Swift, Kotlin, and Go are also gaining popularity in the web development industry, and of course the list would not be complete without Good Ole HTML5 and CSS.