Fontmatrix ships with a set of sample texts in various languages and scripts and lets you add your own (see the section called “Samples collection”). To pick a text from the collection click the Samples collection button to reveal a sidebar with the available samples.

Use Ctrl+wheel to zoom and the middle mouse button to pan. Click and drag to draw a zoom rectangle. A single click anywhere on the canvas resets to 1:1 zoom.

By default Fontmatrix uses FreeType to render text — switch to Vector in the Display settings sidebar for smooth rescaling.

The World is wide options control inline and block progression for non-Latin scripts (Hebrew, Mongolian, etc.).

Click the OpenType features button to reveal a sidebar listing every available OpenType feature in the loaded font, grouped by table and subtable. Toggling a feature re-renders the canvas immediately.

For a variable font the Variations button reveals a sidebar with its axes: pick a named instance from the list, or move the slider of an axis (weight, width, optical size, slant or the designer's own) to any point of its range. The sample, the glyphs chart and the playground show the font at the chosen coordinates; Default takes it back to the position the designer chose. The Info page lists the axes and the named instances, and the font book shows every named instance as a style.

The coordinates you choose are remembered for the next session, until Default is pressed. In the view of a family, a variable font has one row for each of its named instances, drawn at that instance: a click on a row shows the font there, and choosing an instance in the sidebar selects its row.