Phusion BV is a software company known for developing Phusion Passenger, a web and application server that is designed to improve the performance, reliability, and manageability of applications. The software supports multiple programming languages, including Ruby, Python, and Node.js, and is commonly used to enhance server capabilities and optimize resource usage in web environments. Phusion Passenger integrates with major web servers like Nginx and Apache, offering features such as process management, load balancing, and security enhancements.