XRebel vs guava: What are the differences?

# Introduction
This comparison highlights the key differences between XRebel and guava.

1. **Purpose**: XRebel is a tool for Java developers to monitor and debug web applications in real-time, providing insights into performance bottlenecks and database queries, while guava is a set of core libraries that extend and enhance the Java programming language.

2. **Features**: XRebel offers real-time monitoring, profiling, and optimization capabilities for web applications, including hot methods, SQL queries, and HTTP sessions. Guava, on the other hand, provides utilities for collections, caching, primitives, concurrency, and I/O, aiming to simplify common programming tasks.

3. **License**: XRebel is a commercial tool with a paid license model, offering additional support and features, while guava is an open-source project released under the Apache License 2.0, allowing for free usage and modification.

4. **Support**: XRebel offers technical support and regular updates as part of its licensing model, providing assistance and improvements to users, whereas guava relies on community contributions and occasional updates from Google, which maintains the project.

5. **User Base**: XRebel is primarily used by developers and organizations looking for advanced debugging and optimization tools for Java applications, while guava is widely adopted by Java developers seeking efficient and reliable libraries for everyday programming tasks.

6. **Integration**: XRebel integrates seamlessly with popular Java IDEs and web servers, offering a user-friendly interface for monitoring and analyzing web applications, whereas guava can be easily integrated into existing Java projects using Maven or Gradle, providing a lightweight and efficient library for common programming tasks.

In Summary, XRebel focuses on real-time monitoring and debugging of web applications, while guava offers a comprehensive set of core libraries to enhance Java programming tasks.