Folivox

The audiobook workhorse. A powerful tool in a simple interface, free.

Drop in a book, pick a voice, press Render. Get a chaptered audiobook read in any voice you like, on your own computer.

FB2 · EPUB · DOCX · PDF · TXT  →  .m4b / .mp3 with chapters, cover and metadata

Folivox turns a whole book, many hours of it, into a finished audiobook. Out of the box it reads with CosyVoice 3, an open model that clones a voice from a short sample, running entirely on your machine: no account, no subscription, no per-character fee, nothing uploaded.

It is one application with many engines behind it. The book can be read by the free local model or by ElevenLabs, OpenAI, Gemini or Cartesia with your own API key. A narrator voice can come from the bundled catalog, from your own recording, or be designed for this particular book. Everything around the voice, from text clean-up to quality control, chapters and a crash-safe journal, is the same whichever engine you choose.

Use the web studio (folivox ui, in 9 interface languages) or the command line: same pipeline, same results.

Pick one way. Each needs no administrator rights and is safe to run again.

One command (recommended). Open a terminal (macOS: Terminal in Applications → Utilities; Windows: PowerShell from the Start menu; Linux: any terminal), paste the line for your system and press Enter.

macOS and Linux:

curl -fsSL https://raw.githubusercontent.com/vatavale/folivox/main/scripts/install.sh | bash

Windows (PowerShell):

irm https://raw.githubusercontent.com/vatavale/folivox/main/scripts/install.ps1 | iex

git clone https://github.com/vatavale/folivox.git
cd folivox
bash scripts/install.sh

git clone https://github.com/vatavale/folivox.git
cd folivox
powershell -ExecutionPolicy Bypass -File scripts\install.ps1

Open a new terminal window and run:

folivox ui

Your browser opens the studio. Drop a book, choose a voice, press Render audiobook. To stop the studio, press Ctrl+C in the terminal.

The installer sets up everything for you: uv, ffmpeg, the PyTorch build that fits your hardware (NVIDIA GPU, Apple Silicon or CPU) and Folivox. Then it checks your computer and downloads the models (about 6 GB for the voice and 1.6 GB for the quality check) with a progress bar; an interrupted download continues where it stopped. Prefer the terminal to the studio? folivox render book.fb2 puts the audiobook next to the book.

folivox update

Whichever way you installed, this fetches the latest version and keeps your models, voices, settings and unfinished renders. Check the version with folivox --version.

folivox uninstall               # delete the downloaded models (asks first; --dry-run only shows what would go)
folivox uninstall --everything  # also delete your voices and settings
uv tool uninstall folivox       # last step: remove the program itself

It removes only what Folivox created. Your books, audiobooks, ffmpeg and uv are never touched.

Details, options, manual install and troubleshooting: docs/install.md.

Paste a key for any of the four providers in the studio (it is stored in your OS keychain) and they appear next to the local engine. With the model set to auto, Folivox asks the provider which models your key can use and takes the newest one, so new releases are picked up without updating Folivox.

• Ready to use: a bundled catalog of public-domain narrator voices for the book languages, with audition.
• Your own voice: record it with the microphone right in the studio or upload a 6–15 second sample; optional gentle noise reduction.
• Designed for this book: describe the narrator, or press Suggest from my book and a text LLM writes the description from the book itself. An online provider (or the local Qwen3 voice-design model) reads a short text, Whisper ranks the takes, and you keep the best one as a cloning prompt for the free local engine.
• Your library: every voice you add is kept on your computer, with its source and licence, searchable by name and language; star your favourites.

Full guide: docs/voices.md.

The best results we get come from combining one cheap online sample with the free local engine:

1. Generate a voice sample with Gemini 3.8. In the studio: voice gallery → Generate a voice sample → Gemini, describe the narrator (or press Suggest from my book), generate a few short takes. With a paid Gemini key this costs well under one cent (about $0.0023 per 10 s of audio on the paid tier); Google also has a free tier.
2. Keep the best take (Whisper ranks them) as a voice in your library.
3. Render the whole book locally with CosyVoice 3 cloning that voice: free, unlimited, offline.

You pay once for about ten seconds of a top-quality voice, and the open model reads the remaining hours with it. CLI equivalent:

export GEMINI_API_KEY=…
folivox voices design narrator -g gemini --mode design --lang en --describe "calm, warm audiobook narrator" --keep takes/
folivox render book.epub --voice narrator

Reading the whole book with a commercial engine still sounds better than local cloning. For that we recommend Gemini 3.8 Flash TTS: the best narration in our experience and at the same time one of the cheapest engines, about $0.8 per hour of audio at list prices (October 2026; a ten-hour book is roughly $8). Folivox shows the estimate before you start and can stop at a spending cap:

folivox render book.epub --tts gemini --tts-mode design --tts-describe "calm, warm audiobook narrator" --max-cost 10

Prices, limits and terms of all four engines: docs/cloud-engines.md.

Drop a book: chapters, language, cover, details and estimated length.	The voice for your book: the best match is picked automatically; audition others, record your own or generate one.
Done: the file, its length and how long it took.	The bundled voice library: filter by language and sex, audition, star favourites.

_{Demo render on a public-domain text (Alice's Adventures in Wonderland); timings are illustrative.}

• Free for real. The local engine has no limits and no bill; online engines are an option, not a requirement.
• A workhorse for long books. Resumable, crash-safe, quality-checked, with a time forecast: start a ten-hour book and walk away.
• Speaks every book's language properly. A text normaliser for each of the 9 languages reads numbers, dates, money, units and roman numerals the way a narrator would, with gender and case agreement.
• Simple outside, deep inside. A few clicks in the studio; every option is still there in the CLI.
• Any voice, consistent to the last page. Yours, a bundled one, or one designed for the book.
• Honest about what leaves your computer. Online use is opt-in, labelled, estimated and capped.
• Open and replaceable. Apache-2.0 and small provider interfaces: when a better model appears, plug it in.

folivox inspect book.epub                     # chapter tree, size, estimated duration
folivox book.fb2 -v me.wav -o book.m4b        # render the whole book with your voice
folivox book.fb2 -c 1-2 --preview 600         # a quick test: chapters 1–2, first 600 characters each
folivox book.pdf --mp3 -o out/                # one mp3 per chapter
folivox render book.epub --tts openai --tts-voice coral --max-cost 5   # an online engine with a cap
folivox voices                                # your voice library
folivox doctor --bundle                       # check the setup / write a redacted support bundle
folivox bench                                 # speed test: characters per second on each device (CPU, CUDA, MPS)

folivox bench synthesises one short fragment on every device it finds, each in its own process, and prints characters per second, RTF and peak GPU memory, so you can see what actually helps on your machine and compare machines (--devices cpu,cuda picks devices; CUDA is tried even if auto would skip a small GPU).

folivox --help, folivox render --help and folivox help <topic> (voices, providers, config, languages, resuming, quality, speed) explain every option. Full list: docs/cli.md.

What hardware do I need? Python 3.10–3.12, ffmpeg and about 7.6 GB for the models. A Mac with Apple Silicon, or Windows/Linux with an NVIDIA GPU or just a CPU. The CPU works but is slower; folivox setup and folivox doctor look at your machine and tell you what to expect.

How long does a book take? It depends on your hardware, so we do not quote a number. The studio shows the audio length before you start, estimates the render time from your own previous runs, and shows the remaining time while it works. Try a preview first to hear the voice on a few hundred characters.

Is my book uploaded anywhere? Not with the local engine (the default): everything runs on your computer and the studio listens on 127.0.0.1 only; the network is used to download the models. Online engines, online voice generation and OpenAI-compatible recognition or LLM providers send text (or audio) to that provider and may cost money; Folivox says so and asks first. Keys live in environment variables or your OS keychain, never in a config file.

Can I stop and continue? Yes, at any time, even after a crash or a power cut: run the same command (or press Render) again.

Whose voice may I clone? Your own, or one you have explicit permission to use. Folivox ships no celebrity or third-party voices and has no feature for imitating real people. The bundled voices are real readers' public-domain recordings from LibriVox; a reader can ask for their recording to be removed, and the voice will then be dropped.

How do I remove it? folivox uninstall deletes the models Folivox downloaded (it shows the list and asks first; your voices and settings stay unless you add --everything), then uv tool uninstall folivox removes the program. Your books, audiobooks, ffmpeg and anything you had before are never touched. Details: docs/install.md.

uv sync --all-extras
uv run pytest -q
uv run ruff check src tests

The CI workflow (.github/workflows/ci.yml) runs lint and the unit tests on macOS, Windows and Linux without model inference. Notes for working on the code: CONTRIBUTING.md.

Found a bug, a mispronounced word or a book that does not open? Please open an issue with the steps to reproduce; for crashes attach the redacted bundle from folivox doctor --bundle. Ideas and feature requests are welcome there too.

Folivox is maintained by one person, so before writing code for a larger change, please open an issue first to talk it over.

Folivox stands on the work of many people who shared it openly. Thank you:

• CosyVoice by the FunAudioLLM team (Alibaba Tongyi Lab): the voice-cloning model and inference code at the heart of Folivox.
• Matcha-TTS and Whisper (OpenAI), parts of which are vendored; faster-whisper and mlx-whisper for the quality check.
• LibriVox and its volunteer readers, who record public-domain books and give the recordings to the public domain; the bundled voices come from LibriVox recordings.
• Qwen3-TTS for local voice design.
• ruaccent (stress and ё), razdel (Natasha project, sentence splitting) and num2words.
• FFmpeg, PyTorch, Hugging Face, PyMuPDF, EbookLib, python-docx, noisereduce, Starlette, Typer, Rich and uv.
• Project Gutenberg for the public-domain text in the screenshots.

Status: early development. Folivox is licensed under Apache-2.0. It vendors a trimmed copy of the CosyVoice inference code (Apache-2.0) and parts of Matcha-TTS and Whisper (MIT); see src/folivox/vendor/README.md and NOTICE. The CosyVoice 3 weights are Apache-2.0 (model card) and are downloaded, not redistributed. Audio produced by commercial APIs is never bundled; its use is governed by the provider's terms.