is 30 days notice enough to kill a paid b2b tool or am i being rude Customer Notice

It depends on one thing: does your data have a future in it.

A $19 notes app, 30 days is generous. A scheduling tool for a clinic has rows dated after your shutdown date - appointments people have already promised to patients. That is not "your service ends", that is "their next quarter needs rebuilding somewhere else, by hand, while they are working".

Practical version of the test: select max(starts_at) from appointments. Whatever that date is, your read-only date should be after it, or you should give people enough runway to move the future-dated rows. For most scheduling tools that lands somewhere between 60 and 90 days, and it is not about politeness.

Read your own terms before you read anyone's opinion. Half of the templates people paste in say 30 days, some say "at any time for any reason", and a few promise 60. If you promised 60 you do 60, and what the internet thinks is normal is irrelevant.

Do 60 and stop billing on day one of the 60.

The notice period costs you nothing if there is no money moving. Nobody in the history of software has been angry about too much notice; plenty of people have been furious about being charged for a lame duck. Two months of free service also buys a lot of goodwill from people who might otherwise be loud about it.

The number of days matters less than the export. Thirty days with a one-click complete export beats ninety days with "email us and we will send a CSV". A year later nobody remembers how long the notice was. They remember whether they got their stuff out.

Annual plans change the maths. If someone paid in January and you close in March you are refunding pro rata, and you should say so in the first email or you will answer that same question forty times.

Clinics work in quarters. Land the end date on a quarter boundary and half the pain goes away for free.