Audacity 4.0 rebuilds the application interface on Qt with native high-DPI rendering and many quality-of-life improvements. The new clip-editing model allows direct selection of clips, grouping, and free movement between mono and stereo tracks. Moving a clip over another replaces the overlapped part instead of blocking the move.

Splitting has a dedicated tool with split, split-cut, split-delete, split at silences, and split to new track options. Paste handles more cases automatically, creating tracks when needed. Alignment guides, sample-boundary snapping, and per-project snap settings have been added.

The interface includes Modern, Classic, and Music workspaces with light, dark, and high-contrast themes. The separate Select, Envelope, Draw and Multi-tool modes have been removed; their functions are now context-sensitive. Playback and recording have been rebuilt with revised loop boundaries and punch-and-roll recording.

The new .aup4 project format replaces .aup3, which opens and converts without changing the original file. Some Audacity 3 features like Time Tracks and Note/MIDI tracks are not available in 4.0.