Looking for a good job alert tool/website for companies I select.

I have shortlisted 50-70 companies and want to apply to roles in those on priority as soon as they are posted. Plus, I want to know immediately of ANY new job posted in entire US in those companies.

Job alerts on company websites are not working that well cuz half the companies don't have it. Also, even if I set frequency to daily, I believe it is a bit late. LinkedIn Job Alerts is useless cuz I need to mention the role too and it has to be an exact match.

Eagerly looking for help on this. Thank you!