I am looking for information related to test preparation for the GRE.
- math questions with answers (GRE subjects)
- vocabulary tests
Anki is a flashcard software.
It has a large collection of shared decks, curated by the Anki community.
In particular, Anki has many decks of GRE content:
That list contains a few false positive, but when you filter them out you can see that there are about 120 decks about GRE:
Each deck is a collection of questions and answers.
Quality and focus varies from one to the other.