Wikidata is a companion to Wikipedia that captures a substantial part of the information about most Wikipedia entities in machine-readable structured form. In addition to directly representing information from Wikipedia itself, Wikidata also cross-references how additional information about these entities can be accessed through APIs on hundreds of other websites.

Today, many web sites offer third-party access to their data through web APIs. But manually encoding URLs with arbitrary endpoints, parameters, authentication handshakes, and pagination, among other things, makes API use challenging and laborious for programmers, and untenable for novices. In addition, each site offers its own idiosyncratic data model, properties, and methods that a new user must learn, even when the sites manage the same common types of information as many others.

Mavo is a small extension to the HTML language that empowers non-programmers to create simple web applications. Authors can mark up any normal HTML document with attributes that specify data elements that Mavo makes editable and persists. But while applications authored with Mavo allow users to edit individual data items, they do not offer any programmatic data actions that can act in customizable ways on large collections of data simultaneously or that modify data according to a computation. We explore an extension to the Mavo language that enables non-programmers to author these richer data update actions. We show that it lets authors create a more powerful set of applications than they could previously, while adding little additional complexity to the authoring process. Through user evaluations, we assess how closely our data update syntax matches how novice authors would instinctively express such actions, and how well they are able to use the syntax we provided.

Large-scale discussions between many participants abound on the internet today, on topics ranging from political arguments to group coordination. But as these discussions grow to tens of thousands of posts, they become ever more difficult for a reader to digest. In this article, we describe a workflow called recursive summarization, implemented in our Wikum prototype, that enables a large population of readers or editors to work in small doses to refine out the main points of the discussion. More than just a single summary, our workflow produces a summary tree that enables a reader to explore distinct subtopics at multiple levels of detail based on their interests. We describe lab evaluations showing that (i) Wikum can be used more effectively than a control to quickly construct a summary tree and (ii) the summary tree is more effective than the original discussion in helping readers identify and explore the main topics.

Many people can author static web pages with HTML and CSS but find it hard or impossible to program persistent, interactive web applications. We show that for a broad class of CRUD (Create, Read, Update, Delete) applications, this gap can be bridged. Mavo extends the declarative syntax of HTML to describe Web applications that manage, store and transform data. Using Mavo, authors with basic HTML knowledge define complex data schemas implicitly as they design their HTML layout. They need only add a few attributes and expressions to their HTML elements to transform their static design into a persistent, data-driven web application whose data can be edited by direct manipulation of the content in the browser. We evaluated Mavo with 20 users who marked up static designs---some provided by us, some their own creation---to transform them into fully functional web applications. Even users with no programming experience were able to quickly craft Mavo applications.