Chronon Systems have started a public beta of the Chronon time travelling debugger for Java. Chronon is a revolutionary new technology for Java that consists of:

• A “flight data recorder” for Java programs which can record every line of code executed inside a program and save it to a file on the disk. The file can be shared among developers and played back in a special time travelling debugger to instantly find the root cause of an issue.This also means that no bugs ever need to be reproduced!
• A Time Travelling Debugger, with a novel UI that plugs seamlessly into Eclipse, which allows you to playback the recordings. It not only steps back and forth but also to any point in the execution of your program.

The current beta is meant for internal use, so that developers can  try it out in scenarios like development, support, QA, etc. However this release is not suitable for use in production level scenarios where performance is an extremely high level priority.

The main purpose of this beta is to get developer feedback, as the team state in their blog: 

This is a beta in the true sense that we really want you to evaluate the robustness of the recorder and the time travelling debugger.  We want to hear from you if the recorder crashes under some circumstances or the level of performance you would like it to reach. Similarly for the time travelling debugger, we really want to hear your opinion on whether it helps you find root causes of bugs faster than a traditional debugger.

Keep in mind, 'beta' means things will be a little incomplete and sharp around the edges. For one, we the current eclipse plugin doesnt have great J2EE integration (will be there in final release). 

Even though we have tried to keep the UI of the debugger familiar to that of the traditional debugger, when you are in hardcore debugging mode you will realize how different it actually is. We know that this new UI will cause some surprises for the new users. Thus we have added a bunch of videos showcasing some scenarios how Chronon should be used