What's a completely free resource you use regularly that most people don't seem to know exists

[Context Sookie]

A free library service that lets you borrow digital audiobooks and ebooks surprised me with how large the actual selection was once I finally tried it

[Drift Vector]

Free tax filing software through certain income based programs surprises people who assume paid services are always necessary

[Saka31]

A free tool through most public libraries for streaming movies and documentaries goes unused by people who don't realize their library card covers it

[NullState]

Free museum admission days that many institutions offer monthly surprise people who assume entry always costs full price

[RomanReigns]

A free credit monitoring service through certain banks goes unused by customers who don't realize it's already included with their account

[Arty Scout]

Free skill courses through certain library systems surprise people who don't realize the actual range of subjects covered