I tested Reply Chime again after the developer responded to my feedback and released an updated version.
I regularly run several long ChatGPT conversations in parallel, so accurate completion notifications are very important to my workflow.
I previously had problems finding a solution that worked reliably enough, and I eventually developed my own open-source Firefox extension to experiment with ChatGPT's completion notifications and multi-tab behavior.
That development process made me realize that this problem is much more complicated than it first appears, especially when the same completion notification can surface across multiple ChatGPT tabs.
After testing the updated Reply Chime with my real workflow, it now meets my needs. I have therefore paused active development of my own extension and now recommend Reply Chime as the alternative in my project's README.
I especially appreciate that the developer responded to feedback and continued improving the extension. That kind of responsiveness made a real difference here.
Thank you for the update.

Thanks again for the recent update. Reply Chime is now working well with my multi-tab ChatGPT workflow.
One small suggestion: the current notification sound feels a little sharp to me during long work sessions. Would you consider adding a few alternative sounds, such as a softer chime or bell, or an option to choose a custom notification sound?
The current volume control helps, but having a softer tone option would make the extension even better for frequent use.