JSPWiki relies on Apache code for many important functions, notably for file uploading (commons-fileupload), content indexing (Lucene), HTML element construction (ECS), HTTP client request and response processing (commons-httpclient), and XML request processing (XMLRPC).

Apache is by far the single most prominent source of third-party JARs that JSPWiki uses. The complete list of Apache packages the JSPWiki runtime WAR includes is:

Apache Log4J:                 log4j-1.2.14.jar
Apache Lucene:                lucene.jar, lucene-highlighter.jar
Apache XML-RPC:               xmlrpc.jar
Jakarta Taglibs:              jakarta-tablibs-standard-1.1.2.jar, jakarta-taglibs-jstl-1.1.2.jar
Jakarta ECS:                  ecs.jar
Commons Lang:                 commons-lang-2.3.jar
Commons IO:                   commons-io-1.4.jar
Commons HTTPClient:           commons-httpclient-3.0.1.jar
Commons FileUpload:           commons-fileupload-1.2.1.jar
Commons Codec:                commons-codec-1.3.jar

In addition to these libraries, unit and web unit tests use these Apache libraries:

Jakarata Jasper JSP compiler: jasper-compiler-5.5.25.jar jasper-runtime-5.5.25.jar
Xerces XML parser:            xercesImpl-2.6.2.jar
XMLCommons:                   xml-apis-1.0.b2.jar

The JSPWiki project has also demonstrated synergy with Apache by working with helping to fix bugs in Apache software that affected JSPWiki. For example, a bug in Apache Tomcat's package naming restrictions code, which forbade loading of code with the package prefix org.apache.jsp* prevented JSPWiki from using its initial desired package name, org.apache.jspwiki. JSPWiki committer worked with the Tomcat dev team to fix the bug, which was fixed in Tomcat 6.0.19.

Finally, the development team has developed JSPWiki 3.0 to use JSR-170 (Java Content Repository) back-ends for information storage. Although JSPWiki by necessity ships with a limited JCR implementation called Priha (developed by Janne Jalkanen), our intention is to ensure that JSPWiki 3.0 also works smoothly with Apache Jackrabbit.