There are 2 books in the The Library of Ever series. The newest book is Rebel in the Library of Ever which came out in 2020.

1
The Library of Ever

Book cover of The Library of Ever
With her parents off traveling the globe, Lenora is bored, bored, bored - until she discovers a secret doorway into the ultimate library. Maze like and reality-bending, the library contains all the universe's wisdom. Every book ever written, and every fact ever known, can be found within its walls. And…
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2
Rebel in the Library of Ever

Book cover of Rebel in the Library of Ever

Rebel in the Library of Ever continues Zeno Alexander’s acclaimed middle-grade fantasy series with a dangerous takeover of the magical Library as our heroine fights to make knowledge free for everyone.

Lenora returns to the magical Library―which holds every book ever known on its shelves. But she discovers the Library…