1. JavaScript : JavaScript is one of the most popular programming languages and is widely used for both front-end and back-end development. It is the primary language for building dynamic web pages and is supported by all major browsers. In addition, JavaScript is also used for server-side development using Node.js.
2. Python : Python is a versatile and powerful programming language that is widely used in web development. It is particularly popular for back-end development and can be used to build a wide range of web applications. Python is known for its simplicity and ease of use, making it a great choice for beginners.
3. Java : Java is a popular programming language that is widely used for building enterprise-level web applications. It is known for its stability, security, and performance, making it a great choice for building large-scale web applications. Java is also platform-independent, which means that it can be run on any operating system.
4. Ruby : Ruby is a programming language that is known for its simplicity and expressiveness. It is often used for building web applications with the Ruby on Rails web framework, which is known for its convention over configuration approach. Ruby is a great choice for building web applications quickly and easily.
5. C# : C# is a programming language developed by Microsoft and is widely used for building web applications on the .NET platform. It is similar to Java in many ways and is known for its performance and scalability. C# is a great choice for building web applications that need to integrate with other Microsoft products and technologies.

In conclusion, these five programming languages are essential for any web developer in 2023. JavaScript, Python, Java, Ruby and C# are widely used and in-demand in the industry, and a solid understanding of these languages can open up a wide range of opportunities for web developers. It’s important to note that each language has its own strengths and weaknesses, so it’s important to choose the right one for the job at hand.