Web-based document circulation tool (Open Source). Users are able to define "documents" which are sent step by step to every user in a list.

Open source graphical workflow process editor supporting WfMC specifications. Can be used to view and edit XPDL files.

Open Source workflow engine and client applications (admin and worklist handler) based on WfMC and OMG specification.

Open Source workflow management system based on J2EE. It runs on a JBoss application server and is available under the Lesser General Public License (LGPL). Contains project description, system documentation and links to the source code. Maintained by Tom Baeyens.

Maintained by Dutch consultants Topicus. They list version, language, status and license of more than a dozen open source workflow projects, and provide a short summary of each project's focus. Owner Michiel Schipper also maintains a Blog on workflow related topics.

Open source workflow engine written in Java, designed to execute workflow definitions written in XPDL. Designed to be embedded in an application, used as a stand-alone server, or used in a J2EE container.

Open source workflow engine which models activity-based workflow. Most of the information and documentation of OpenFlow is in Italian, but the English-language introduction is well-written.

Java-based open source workflow engine.

WfMOpen is a lightweight J2EE based workflow engine with OMG like API, using XPDL as process description language. Open Source.

The wftk is a general-purpose open-source workflow engine and toolkit, designed to work with diverse interfacing systems (databases, mail systems, and user interfaces).