Content Repository API for Java (JCR) is a specification for a Java platform application programming interface (API) to access content repositories in a uniform manner.[1][failed verification] The content repositories are used in content management systems to keep the content data and also the metadata used in content management systems (CMS) such as versioning metadata. The specification was developed under the Java Community Process as JSR-170 (Version 1),[2][3] and as JSR-283 (version 2).[4] The main Java package is javax.jcr.