A house with a few hundred books has a library and no catalogue. This page makes one. Type an ISBN or a title and the record comes back from Open Library with authors, year, publisher, subjects and a cover; or enter books by hand, paste a list, or import a Goodreads or LibraryThing CSV. Then shelve them, mark who is reading what, record who borrowed which book and when, and look at the shelves as a subject map rather than a list. The catalogue lives in this browser and nowhere else; export it as JSON to keep a copy, move it to another machine or hand it to the next generation.
Add books
Paste a list, or import a CSV
Book
Select a book on the right to edit it, or add one above.
The catalogue
Saved in this browser as you go. Nothing is sent anywhere except the ISBN or title you look up, which goes to openlibrary.org.
Each dot is a book; two books are joined when they share a subject. The layout is a force simulation run in the page; drag nothing, hover for the title. Books with no subjects sit out.