ai1y Docs

Documentation

Read along, make books, build on the format

Everything ai1y does today and how to use it, in a guide for each of the things you might want to do: read a book, make one, or build on the open format underneath. For a quick look first, take the tour.

Start here

ai1y, say it “Ally”, turns a book into a read-along: the text stays on the page, a voice reads it aloud, and each word lights up as it’s spoken. Its format is open, and it’s in early development.

  • To read a book, open the reader at ai1y.co/read, pick a book and press Read to me. There’s nothing to install. The guide for readers shows everything the reader can do.
  • To make a book from an EPUB, with a narrator and a voice for each character, use the creator studio. The guide for creators walks through it.
  • To build on ai1y, in your own reader, app or tools, start with the format in the guide for developers. To drive the creator studio from your own programs or an AI agent, see the API docs.

How ai1y fits together

There are four pieces, and each works on its own:

  1. A book goes in. ai1y reads EPUB, the standard e-book format, including thousands of free classics from Project Gutenberg.
  2. The builder makes an ai1y book. ai1y-build cuts the text into sentences, narrates each one, listens back to time every word, and packs the result into small, hash-checked files.
  3. The reader plays it. A web app for phones, tablets and computers, with the words lighting up, a library, settings and offline reading.
  4. The format ties them together. An open, documented set of files that any app can read, so a book made with ai1y isn’t locked to ai1y.

The creator studio sits on top of the builder, for anyone who wants to choose voices and fix lines by ear.

Licenses and voices

  • The format is open. The specification is CC BY 4.0; its schemas and test vectors, ai1y-core, the Rust crates and the reader are Apache 2.0. Anyone can read, write and build on ai1y books, for any purpose.
  • The tools (the builder, voices, creator studio, catalog, ask and Yoto tools, and the MCP server) are under the Functional Source License. Families, schools, nonprofits and creators can use and self-host them free, including to make books they sell; the one thing not allowed is offering them, or something like them, as a competing commercial product or service. Each release becomes Apache 2.0 two years after it’s published.
  • Breeze TTS 2 is licensed for research and non-commercial use. Books narrated with it are offered free, with the voice credited and labeled as AI, and nothing they appear beside is sold or carries ads. The planned hosted service will use a commercial license of Breeze TTS 2.
  • Every narration says it’s AI. The reader names the model that made each voice under the play button.
  • Books you bring must be DRM-free. ai1y never removes DRM. Narration made from a book you own is for you; an overlay book lets others line up their own copies instead of sharing yours.
  • Public-domain books from Project Gutenberg are built without reading Gutenberg’s header, footer and license, which belong to its own copies rather than to the book.

This page describes how ai1y handles licenses. It isn’t legal advice.

Questions

Is an ai1y book an EPUB?

No. It is its own set of files, made from an EPUB, so it might not work in your favorite e-book reader today. It supports EPUB by pointing back into the book it came from and keeping the same timing data as EPUB 3 Media Overlays.

The format is open, so you’re not locked in. Its rules are published, anyone can build a reader or a converter for it, and a book made from an EPUB could be turned back into a read-aloud EPUB. We plan to support more formats than EPUB.

Is it for learning to read, or for listening?

Whatever you want from a book. Follow along word by word while learning to read, listen like an audiobook with the words in front of you, or ask a book questions and talk it through. The words stay on the page, and you choose when to listen, follow along or read alone.

Does it work offline?

Reading and narration do, once a book is saved for offline reading. Asking questions uses an online service, which is sent only the question and the passages it needs. The privacy policy has the details.

Which voices can I use?

Breeze TTS 2 today, or your device’s own voice in the reader. The engine layer is pluggable, so other engines can be added without changing the format or the reader.

Can I put ai1y books in my own app?

Yes. The format is open and documented, the Rust core runs natively and in the browser, and the on-device service gives an app a verified cache with offline books.

Where do I report a problem or suggest a change?

Write to support@ai1y.co. Feedback on the format is especially welcome.