Pick your path: private on your phone, or faster with a free LLM

What stays on your phone

• Offline mode: import a finished book file (.tar.gz or .zip) and read and listen with no server or account.
• On-device mode: your phone converts the PDF with a local model and a neural voice. After a one-time model and voice download, nothing leaves the device.
• Guests can use both. No sign-in is required to read, import or convert on the device.

What leaves your phone, and only if you turn it on

• Cloud helper sends the hard passages (equations, figures, tables) to the LLM you configured.
• Use the cloud LLM for every passage sends all of the book’s text to that provider. Leave it off for private books.
• Research characters online sends only the book title and character names, never the book’s text.
• Google Drive sync stores your finished books in your own Drive.

Free LLM providers may log prompts. Use the on-device model for anything confidential.

Novel / characters

Keeps the original prose word for word, splits dialogue by speaker, and gives each named character their own delivery. Speakers are recognised from explicit tags such as Alice said or “Hello,” Bob replied. Anything uncertain is read by the narrator.

Beyond male and female, each character can have an age (child, young, adult, elder) and a temperament (calm, cheerful, stern, gruff, gentle, energetic, mysterious). Age and temperament change speed, pitch and expressiveness, and spread characters across the available voices.

Set them yourself in Character voice overrides, one per line:

Alice=child cheerful
Mad Hatter=Michael, elder, gruff
Queen of Hearts=female stern

Names match without regard to case, and a short name such as “Hatter” also matches “Mad Hatter”. Overrides that match nobody are reported in the conversion log, so typos are easy to spot.

Let the web figure it out

Turn on Research characters online. Firebrat finds the book’s Wikipedia article and asks your LLM to describe each character’s age and temperament, then applies it. Only the title and character names are sent, never the book’s text. This needs an LLM URL, key and model (see above) or a server. Your own overrides always win over research, and any failure simply skips the step.

Check who was found

After a novel is converted, open Cast & voices (the people icon in the reader, or long-press the book in your library). It lists every speaker with their number of lines, shows what share of the book’s dialogue was attributed to a named character (the rest is read by the narrator), and shows each character’s age, temperament and voice, plus what the web research found and missed. A character appears only when the book tags their lines (“Elizabeth said”), so the percentage is the honest measure of coverage.

Illustrated / technical

For textbooks, datasheets and papers: figures, tables and formulas stay on screen and highlighted exactly while they are being discussed, and Source page opens the original PDF page.

1. Sign in with Google from the menu (Drive sync needs an account; reading and local conversion do not).
2. Open Conversion settings. Under Get finished books from where? choose My Google Drive, then tap Connect Drive and approve the permission.
3. New books back up to a Firebrat folder in your Drive, one zip per book. Tap Sync now on another device to pull them, or use Per-book backup to choose which books to upload.
4. Open Menu › Sync & backup to keep your reading position in each book across devices.

Privacy: Firebrat asks only for access to files it creates itself (the “drive.file” permission). It cannot see or change anything else in your Drive. You can turn sync off at any time.