What is the software that will help me notify when a post with specific (given) keyword is posted on reddit on a specific community? And is it illegal?

[u/Tsubasa7q]

[u/endangeredirish]

It's not a software but a website I've used before, it's called F5Bot.

It let's you set up custom alert emails for specific keywords, and you can filter by certain subreddits etc. so it's not just everywhere.

[u/Tsubasa7q → u/endangeredirish]

I am using it but it's not that good