FYI: I managed to get Cactus 1.7.1 run with the newest Commons Httpclient Release (3.0 RC3). Here's a step by step HOW TO: 1.) Just check aut the source and run ant. After the build all required libraries have been downloaded. 2.) Make a compy of build.properties.default named build.properties. 3.) Change the value of the property ${commons.httpclient.jar} to the location of your httpclient 3.0 jar. 4.) Run ant again. (The build will probably fail during testing, but this didn't matter to me). 5.) In the directories framework\dist-13\lib ( for J2EE1.3) / framework\dist-14\lib (for J2EE1.4) and integration\ant\target-13 (for J2EE1.3) / integration\ant\target-14 (for J2EE1.4) you will find 1 jar each. These (cactus-1.7.1.jar and cactus-ant-1.7.1.jar ) is everything you need. 7.) To make them run make sure the newest required libraries are placed in the class path. I also had to do minimal changes in my ant build file. Have fun Marcel