The Open Siddur Project (Hebrew: פרויקט הסידור הפתוח, IPA: pʁojeqt hassidduʁ hapatuaħ) is an open-source, web-to-print publishing and digital humanities project intent on sharing the semantic data of Jewish liturgy and liturgy-related work with free-culture compatible copyright licenses and Public Domain dedications. The project collaborates with other efforts in open-source Judaism in sharing content and code, advocates among related user-generated content projects to adopt Open Content licensing, and solicits copyright owners of related liturgical materials to share their work under free-culture compatible terms.