Free and open source, Juxta Commons is an online workspace for comparing multiple witnesses to a single textual work, privately storing collations, and sharing visualizations. Originally offered as a downloadable Java-based application developed by the Applied Research in ’Patacriticism group at the University of Virginia in 2005, Juxta was taken up by NINES (http://nines.org) and transformed into a web service. This open-source API modularizes the sequence of steps required for digital collation and offers more options for working with XML documents. In addition, the NINES R&D team created the interface for Juxta Commons, a destination site for collation on the web. Juxta Commons offers three visualizations of the differences between a group of texts: the heat map (an overlay of the texts with differences highlighted by color), the side-by-side view (two texts visualized with lines connecting the sites of difference), and the histogram (a global view of the text illustrating the portions with the most change across versions). It is also compatible with TEI Parallel Segmentation, so that users can upload their encoded files and make use of Juxta’s visualizations, or those with text or XML files can export their collations as a digital critical apparatus. The interface streamlines the workflow of the original desktop application, and allows the user to edit their sources, filter the XML content included in a given collation, and share their results in a number of different ways. Even though the tool provides sophisticated options for working with texts (XML and TXT), our goal in designing Juxta Commons was to allow teachers, scholars, programmers and any other users curious about variants between documents the ability to create, collate and share their findings with others without requiring any extra software downloads or logins. In taking Juxta to the web, NINES has transformed it into a rhetorical as well as analytical tool, enabling initial discoveries to be interrogated, explored, and ultimately offered as a new kind of evidence for scholarly arguments. Instead of relying upon footnotes or links in a digital edition, a scholar can embed their collations within the argument itself, targeting sites of interest, and encouraging readers to explore the full visualizations on their own. Even as it presents some exciting opportunities for students of book history and textual criticism, Juxta Commons also broadens the scope of interest in collation to the many different kinds of texts on the web. Speeches and transcriptions, Wikipedia article versions, news releases, Google Books and HATHI Trust texts: all these require the kind of authentication and analysis that Juxta Commons makes possible. Please visit the site juxtasoftware.org to learn more, and to find sample sets to spark your creativity. Juxta Commons is a project of NINES, supported by the University of Virginia and developed by Performant Software Solutions, LLC. Additional support for the development of Juxta Commons was provided by a Google Digital Humanities Research Award. This poster was originally presented at DH2013 on July 17, 2013.