RSS (really simple syndication) is pretty much the industry standard for feed readers. You'll find RSS feeds in almost every app imaginable.

RSS by Zapier

Tumblr is a microblogging platform and social networking website which allows users to post multimedia and other content to a short-form blog.

Tumblr

Mola

Anytime a new item is created in RSS, create link post in Tumblr.

Works for a simple command (posting from a tag with dedicated RSS), not specific ones like "Podfic in X fandom"


AO3 feed for Tumblr - Link post

“Anytime a new item is created in RSS, create link post in Tumblr. Works for a simple command (posting from a tag with dedicated RSS), not specific ones like "Podfic in X fandom" ”

Trusted at companies large and small

This Zap works in 2 steps …

Anytime a new item is created in RSS by Zapier

Create link post in Tumblr

This Zap uses the following 2 apps

RSS by Zapier

Tumblr

RSS by Zapier + Tumblr