I know of others but I'm not sure they are still maintained till date. If you have recommendations for this service, you can drop and I will gladly add to Op.
Well, I have a notification bot, but even so, it continued to use a lot of the fantastic tool that the forum itself has:
WatchlistWhenever I enter the forum, and before searching for new topics, I look at all the topics where I've already replied and have new responses. Then I answer the ones I have to answer.
Now, I agree that sometimes we wait for feedback or response from some users, and it seems like they just disappeared. I don't know if this is a widespread problem or not. But I feel it sometimes, no doubt.
Personally, I always try to respond and continue the conversations, when this is relevant.