citeproc-js (coded in JavaScript) is currently the most complete CSL 1.0 processor, and is used by Zotero and Mendeley. Other CSL 1.0 processors, in various degrees of completeness, include citeproc-hs (Haskell), citeproc-php (PHP), citeproc-py (Python, by Bruce D’Arcus), citeproc-py (Python, by Brecht Machiels) and citeproc-ruby (Ruby).