Every exchange will alert you when a price crosses a level. That is the least informative thing a computer can tell a trader, because the price crossing a round number is not an event; it is arithmetic. A more useful alert watches a condition that takes work to compute.
Conditions worth watching
The flip moving is one. The level where dealer positioning changes sign is not a price you picked, it is a property of the book, and when it moves a long way the character of the session changes with it. Funding diverging across venues is another, because it is a positioning imbalance that usually resolves rather than persisting.
A wall building or draining at a particular strike is a third. So is realised volatility crossing out of the band it has been sitting in for weeks. None of those are visible on a chart, and all of them are computable on a schedule.
The alert should arrive where you work
An alert that requires you to be looking at a dashboard is not an alert. A webhook is the general answer, because everything downstream — a chat channel, a phone, a script that flattens a position — can receive one.
It should carry the reason
A notification that says only “condition met” forces you to go and reconstruct why. A good payload includes what was being watched, what the value is now, what it was when the alert was armed, and when the reading was taken. That last one matters more than people expect: an alert delivered four minutes late is a different fact from one delivered instantly, and only a timestamp tells them apart.
And it should stop
An alert that fires every evaluation cycle while a condition holds is noise by the third message. Either it retires after firing, or it waits out a cooldown. Both are defensible; silently spamming is not.