Developing real-time audio applications, particularly those with an element of user interaction, can be a difficult task. When things go wrong, it can be challenging to locate the source of a problem when many parts of the program are connected and interacting with one another in real-time.

We present a time-travel debugger for the Flow Web Audio framework that allows developers to record a session interacting with their program, playback that session with the original timing still intact, and step through individual events to inspect the program state at any point in time. In contrast to the browser’s native debugging features, audio processing remains active while the time-travel debugger is enabled, allowing developers to listen out for audio bugs or unexpected behaviour.

We describe three example use-cases for such a debugger. The first is error reproduction using the debugger’s JSON import/export capabilities to ensure the developer can replicate problematic sessions. The second is using the debugger as an exploratory aid instead of a tool for error finding. Finally, we consider opportunities for the debugger’s technology to be used by end-users as a means of recording, sharing, and remixing ideas. We conclude with some options for future development, including expanding the debugger’s program state inspector to allow for in situ data updates, visualisation of the current audio graph similar to existing Web Audio inspectors, and possible methods of evaluating the debugger’s effectiveness in the scenarios described.