[asjo]

rachelbythebay has a service and a series of blog posts about the technical side of this, starting at https://rachelbythebay.com/w/2024/05/27/feed/

TL;DR: readers should not poll more often than once and hour, use ETag and If-Modified-Since to determine whether to download the full feed again.

Which items you have seen previously is something the feed reader keeps track of.

[account42]

Polling every hour is excessive and will get you temp-blocked on some sites.

It really depends on you but IMO for most feeds polling once a day is plenty.

[fire_lake]

> Which items you have seen previously is something the feed reader keeps track of.

Is there a particular field that can be used as an identifier?

[asjo]

Yes, the `guid` field in RSS and the `id` field in Atom.