Trazu is a digital painting and drawing app with tools for inspecting a work while painting. It provides four study views that display the canvas in grayscale values, temperature, saturation, or contrast. Users can also place composition guides over the canvas, including the rule of thirds, diagonals, the golden section, the golden spiral, golden triangles, rabatment, dynamic symmetry, and the harmonic armature. These views and guides can be used during painting and are not included in exported artwork. The app offers nine painting and drawing mediums, including oil, watercolor, ink, charcoal, chalk, pastel, and pencil, along with different brush tips and tools. Paint can mix with wet color already on the canvas; the simulated materials include features such as thick oil, watercolor pooling, and dry media responding to paper grain. Users can choose from twelve paper textures or import a photo to paint over. Pressure affects brush width, while drawing speed affects how paint is applied. A typical workflow is to select a medium and paper, paint or work over an imported image, and switch to a study view or composition guide to assess values, color, contrast, or layout before continuing. The app is intended for painters practicing or learning fundamentals, including those who want to work on their paintings away from a studio. It works offline and is sold as a one-time purchase rather than a subscription. The developer states that drawings remain on the user’s device and are not sent to a server; anonymous usage statistics and crash reports may be collected.