LittleProxy is a high performance HTTP proxy written in Java atop Trustin Lee's excellent Netty event-based networking library. It's quite stable, performs well, and is easy to integrate into your projects. From Maven this as simple as:

        <dependency>
            <groupId>org.littleshoot</groupId>
            <artifactId>littleproxy</artifactId>
            <version>0.4</version>
        </dependency>

If you have questions, please visit our Google Group here:

https://groups.google.com/forum/#!forum/littleproxy

The main LittleProxy page is here:

http://www.littleshoot.org/littleproxy/