How to Convert Any Book to an Audiobook with Bitcoin Lightning
Upload EPUB, PDF, or TXT. Choose your chapters. Optionally translate to another language. Pick a quality tier. Get an M4B audiobook with chapter markers.
For Humans
Use the web UI — upload, choose, pay, download.
Audiobook services like Audible charge $15/month and only carry published titles. Professional narration of your own manuscript costs $200-400 per finished hour. With Sats4AI, you upload any book file and get a complete AI-narrated audiobook for a few thousand sats — roughly what you would spend on a cup of coffee. You can even translate the book to another language before narration, so a single English manuscript becomes a Spanish, French, or Japanese audiobook in one step.
Self-published authors
You wrote the book — now give readers an audio version. Upload your manuscript and have a full audiobook ready in under an hour, at a fraction of studio costs.
Personal reading
Have a DRM-free ebook you prefer to listen to? Convert it to audio and listen on your commute. Supports EPUB, PDF, and plain text files.
Narrate in your own voice
Use voice cloning to capture your voice once, then select the Voice Clone tier — the entire book will be narrated in your voice.
Study materials
Convert textbooks, research papers, or course notes to audio. Listen while exercising, commuting, or doing chores — retain more through a second channel.
Foreign language audiobooks
Have a book in English but want to listen in Spanish, French, or Japanese? Use the built-in translation option — the book is translated chapter by chapter before narration, so you get a native-language audiobook from any source file.
Language learning
Translate a familiar book into the language you are studying, then listen to the audiobook. Hearing a story you already know in a new language builds vocabulary and comprehension naturally.
How It Works
Upload your book
Upload an EPUB, PDF, or TXT file (up to 50 MB). The system extracts chapters from the table of contents, counts characters, and shows pricing for 3 quality tiers.
Select your chapters
Review the chapter list with checkboxes. Front and back matter (copyright, table of contents, etc.) is automatically detected and deselected. Toggle any chapter on or off — the price updates in real time.
Translate (optional)
Choose a target language from 40+ options. The book is translated chapter by chapter before narration. If the language is only supported by one TTS model, only that tier is shown. Translation cost is added to the price as a separate line item.
Choose a tier, voice, and pay
Pick from Most Affordable, Best Quality, or Voice Clone tier. Select from 22+ preset voices or paste a custom Voice ID. Pay with Lightning — the exact price reflects your chapter selection and translation.
Track and download
Watch real-time progress as each chapter is translated (if applicable) and narrated. When complete, download an M4B audiobook file with embedded chapter markers — skip between chapters just like a professional audiobook.
3 Quality Tiers
Pricing scales with book length. Below are rough estimates for a typical 500k-character novel (~80,000 words).
TTS 1.5 Mini
- 22 preset voices
- 14 languages
- Fast generation
TTS 1.5 Max
- 22 preset voices
- 14 languages
- Top TTS leaderboard model
Speech Turbo
- 17 presets + custom voice
- 40+ languages
- Use your cloned voice
Supported File Formats
.epub
Standard ebook format. Chapters are extracted from the built-in table of contents (NCX/nav), so only real chapters appear — no title pages or copyright notices. Must be DRM-free.
Text is extracted page by page and grouped into ~20-page chapters. Works best with text-based PDFs (not scanned images).
.txt
Plain text files. If the text contains chapter markers (e.g., "Chapter 1"), they are used to split into chapters — otherwise treated as a single chapter.
For Agents
Automate audiobook creation with the API.
The audiobook endpoint is a two-step API: upload a file to get chapter info and pricing, then pay and start generation. You can specify which chapter indices to include and optionally a target language for translation. The job runs asynchronously — poll the status endpoint until complete, then download the M4B audiobook. Ideal for batch processing, multilingual content, or integrating into publishing pipelines.
Automated audiobook pipeline
An agent monitors a folder for new manuscripts, uploads each one, selects a quality tier, and delivers finished audiobooks — hands-free production.
Document-to-audio for accessibility
Convert internal documents, training manuals, or knowledge bases into audio format for team members who prefer listening over reading.
Course material narration
Convert lecture notes and textbook chapters into audio lectures. Students can listen on the go — improving retention through multimodal learning.
Branded voice content
Clone a spokesperson or character voice once, then produce all audio content in that voice — consistent brand identity across every audiobook.
API Flow
Upload the file (PUT)
Send the book file as multipart form data. The API returns each chapter with title, character count, and an isFiltered flag for front/back matter. Also returns pricing info for all 3 quality tiers.
Create a charge and pay
Calculate the price based on selected chapters and tier. Use the charge endpoint with the amount in sats. Pay the Lightning invoice.
Start generation (POST)
Send the payment ID, file location, selected model, voice, speed, selectedChapterIndices, and optionally translateToLanguage (e.g., 'Spanish'). If a translation language is set, each chapter is translated before narration. The API returns a job ID and poll URL.
Poll for status
GET the status endpoint with the job ID. Track progress — translation phase shows 'Translating: Chapter Title', then TTS shows chapter-by-chapter narration progress. When status is 'completed', download the M4B audiobook.
Chain with Other Services
Convert Your First Book — No Signup Required
Upload EPUB, PDF, or TXT. Select your chapters. Translate to another language if you want. Choose your quality tier. Download an M4B audiobook with chapter markers. All you need is a Lightning wallet.