The UW Interactive Data Lab developed Arquero, a JavaScript library for querying and transforming column-oriented data tables. At its core, Arquero revolves around two key abstractions: data tables and transformation verbs. Data tables, which are similar to Python DataFrames, model each column as an array of values. Data tables are a set of read-only column vectors that can be created from arrays, objects, JSON, CSV’s, and Apache Arrow files. Transformation verbs are table methods that transform data to produce new tables (i.e. from read-only tables). They reuse underlying columns if possible to prevent unnecessary duplication. Supported operations in Aruqero include filters, aggregations, deriving new columns, joins, and more.