Notification service for new software version

Hi,

How do you guys knows when a vendor is publishing a new version of their software ? I am quite curious to know how the PDQ "auto-download" package works behind the scene. How did you guys solve this problem ?

I mean there is multiple product ranging from antivirus, MDM or patch management software that offers this functionality. Is there a global service or a public database out there that we can query to get the last version of a software like the NVD ? 

Surely all these product didn't implement their own fetching API to get the last version of a publish software and surely you guys don't do that by hands !

I guess I could "Brute force" it by writing a script that fetch the product from the site vendor direct download url and compare the version every week or night. That would do the trick but would be quite ineffective in terms of bandwith usage. 

This is for keeping package that are not supported by PDQ up to date. Is there a public API/Database somewhere that keep a record of all this or downloading at regular interval from the site vendor is the only way to go ?

Thanks