klick is an advanced command-line based metronome for JACK. It allows you to define complex tempo maps for entire songs or performances.

• Support for tempo maps, including arbitrary meters, tempo changes, accelerando/ritardando and more.
• Four built-in sounds (borrowed from Ardour, GTick and FreePats), plus ability to load your own samples.
• JACK transport sync support (master/slave).
• Exporting click tracks to audio files.
• Many features can be controlled via OSC.
• No GUI ;)

gtklick is a simple GUI metronome based on klick.