Which AI apps answer questions about the ebook files you own, without spoilers?

01Who is this for?

Readers who keep their books as files: DRM-free EPUBs from publishers or bundles, public-domain classics, PDFs, or documents. If your books live inside Kindle, Google Play Books or Spotify, their built-in tools are simpler: see the best AI reading companion apps by format. If you read print, see Magic Bookmark, which works from a photo of your page and never needs the book file.

02The options at a glance

Prices as published on 4 November 2026. They change; check before you pay.

03Merrilin

Merrilin describes itself as "a reading app for the books you already own, with an AI companion that won't spoil the ending". It reads EPUB and PDF files across desktop, tablet and phone, in the browser and on Android (an App Store version is listed as coming soon). You can ask about a passage or a word, ask questions about the whole book, and compare ideas across several books with answers that include source citations.

On spoilers, its FAQ says: "Merrilin uses your reading position to limit fiction Q&A. Reading boundaries and source citations help you stay in control, but AI answers can still make mistakes." For non-fiction it deliberately draws on the wider book.

Its FAQ also says plainly: "Use files you have the right to upload and read." AI questions need an internet connection.

04Readwise Reader and Ghostreader

Ghostreader is Readwise Reader's AI assistant. Readwise says it can "summarize the document, look up a word (or a term, or a character, or a location)", explain concepts and translate passages, and you can chat with a document or, on web and desktop, across your library with cited answers. You can also write your own prompts.

Readwise does not describe a reading-position limit, so for a novel you are partway through, a "summarize the document" prompt is a whole-book summary. Character look-ups on a selected name are narrower, but nothing in Readwise's documentation says they stop at your page. Use it for non-fiction and finished books, or write a custom prompt that only uses the text you select.

05Basmo

Basmo is a reading tracker that added AI around your own notes. Its App Store listing describes "Ask the book: ask a question and get an answer drawn from your own notes", page scanning, and a Recap that turns your notes into a short listen. Because answers come from what you wrote, they cannot spoil pages you have not read, but they are only as complete as your notes.

06General chatbots with file uploads

ChatGPT, Claude and Gemini accept files you attach. Working from your text is better than working from memory, but none of them knows where you stopped. If you upload a whole novel and ask for a recap of chapter 12, the model has the ending in front of it. The safer habit is to paste only the chapters you have read. See Can Gemini, Claude or Perplexity recap a book?

07What happens to your file?

Each of these services processes your upload on its own servers to answer questions. Before you upload:

1. Read the privacy policy for how long uploads are kept and whether they are used to improve models.
2. Check the App Store privacy label. Readwise Reader's US label lists no data used to track you; Basmo's lists identifiers and usage data as data used to track you. Our privacy label table explains the categories.
3. Prefer services that let you delete your library and account.

08Is it legal to upload an ebook to an AI app?

That depends on your country, the licence of the file and the service's terms, and we cannot give legal advice. What the makers themselves say is useful: Merrilin asks you to use "files you have the right to upload and read". Public-domain classics are the clearest case. Whether a store-bought ebook can be exported as a file at all depends on the store and the publisher.

Authors' groups care about this. The Authors Guild has argued that AI features which turn books into "searchable, interactive products" should be licensed, and objected that Kindle's Ask this Book offered authors no opt-out. Our guide on fairness to authors sets out the arguments.

09Which should you choose?

• You read fiction from your own EPUBs and want spoiler limits: Merrilin is the one that describes a reading-position limit.
• You read articles, non-fiction and documents: Readwise Reader's Ghostreader is built for that.
• You want answers from your own notes: Basmo.
• You read print or audiobooks: you do not need a file at all; Magic Bookmark works from your page or the last phrase you heard, for its supported titles.