Upload a PDF and get a natural AI audiobook in seconds. Multi-column layouts, academic papers, textbooks — all handled automatically. No signup, no limits.
Drag and drop your PDF here
or click to browse
Supports PDF, EPUB, DOCX, TXT, MD, HTML
Purpose-built for PDFs — handles layouts that break every other converter.
Multi-Column PDFs
Two-column research papers, three-column newsletters, mixed layouts with figures and tables. CastReader detects column structure and reads in the correct order. Headers, footers, page numbers, and figure captions are automatically filtered out.
Textbook Ready
Upload a textbook PDF and listen to it on the bus. CastReader preserves chapter structure, skips formatting artifacts, and handles the complex layouts that textbook publishers love. Each chapter becomes a separate audio track you can download.
40+ Languages
Upload a PDF in French, Japanese, German, or Arabic. CastReader auto-detects the language and uses a native AI voice. Perfect for language learners — read along in the PDF while listening to correct pronunciation.
No Software
Open this page, drop your PDF, listen. Works on any device with a browser — Chromebooks, school laptops, library computers. No desktop software to install, no plugins, no account to create.
PDFs are the most common document format on the internet — and the hardest to convert to audio. The reason is simple: a PDF is a visual format, not a text format. It describes where ink goes on a page. A two-column academic paper is just coordinates and glyphs. A scanned textbook is literally a stack of images. Most 'PDF to audio' tools don't actually handle any of this — they call a basic text extraction library, get garbled output, and feed it to a TTS engine. The result sounds like someone reading a phone book.
CastReader's PDF pipeline is different. It uses a multi-pass extraction process: first, it detects the page layout (single column, two-column, mixed). Then it reads text in the correct order — left column before right column, body text before footnotes. It identifies and strips headers, footers, page numbers, running heads, and figure captions. For scanned PDFs, it runs OCR. The output is clean, ordered paragraphs ready for the TTS engine.
The TTS engine itself uses Kokoro, an open-source neural voice model that produces speech natural enough for hour-long listening. It's not a robotic voice from 2018 — it handles emphasis, pauses, and sentence flow in a way that makes academic papers actually listenable. You can download the result as MP3 and listen on your phone, in your car, or on any audio player.
Who converts PDFs to audiobooks? More people than you'd expect. Graduate students listen to research papers during their commute — reading 20 papers a week on screen causes eye strain; listening to 10 of them while walking is sustainable. Law students convert casebook chapters to audio for review. Medical residents listen to clinical guidelines between shifts. Language learners upload foreign-language PDFs and listen along while reading. Teachers create audio versions of reading assignments for students with dyslexia or visual impairments.
The alternatives are expensive. NaturalReader charges $60/year for PDF upload. Speechify charges $139/year. Adobe Acrobat's built-in 'Read Aloud' uses the old robotic system voice and can't handle two-column layouts. Voice Dream Reader is $15 and iOS-only. CastReader is free — no daily limit, no page cap, no signup. Upload a 500-page textbook and it works the same as a 2-page handout.
For PDFs you access regularly online — academic databases, government documents, company reports — consider installing the free CastReader Chrome extension. Instead of downloading and uploading, it reads the PDF directly in your browser tab with paragraph highlighting and speed control. One click, instant playback.
Common questions about converting PDFs to audio
Yes. Upload any PDF — textbooks, research papers, reports, novels, manuals — and CastReader converts it to natural AI audio for free. No signup, no page limit, no daily cap. Other tools like NaturalReader ($60/yr) and Speechify ($139/yr) charge for this feature.
Yes. CastReader's PDF pipeline detects multi-column layouts and reads text in the correct order (left column first, then right). It also filters out headers, footers, page numbers, figure captions, and table labels so the narrator reads only the actual content.
CastReader runs OCR on scanned PDFs to extract text from page images. Results are best with clear, high-resolution scans. Handwritten documents and very old/degraded scans may have limited accuracy. For best results, use PDFs with selectable text.
Yes. After your PDF is processed, each chapter becomes a separate audio track. You can play them in the browser or download as MP3 files for offline listening on your phone, car, or any audio player.
Most PDFs process in under 30 seconds. A 500-page textbook might take a minute or two. You'll see a progress indicator, and the reader opens automatically when processing is complete.
Significantly. Adobe's built-in 'Read Aloud' uses old system voices (robotic and unnatural), can't handle multi-column layouts, and reads page numbers and headers aloud. CastReader uses neural AI voices, detects layout structure, filters noise, and lets you download the audio as MP3.
NaturalReader charges $60/year for PDF upload. Speechify charges $139/year. CastReader is free. Voice quality is comparable — all three use neural AI voices. CastReader's additional advantage: the free Chrome extension reads PDFs directly in your browser tab without downloading, and works on sites that block other tools.
Absolutely. Upload a PDF in your target language — French, Japanese, Spanish, Arabic, or 40+ others. CastReader auto-detects the language and uses a native AI voice. Read along in the PDF while listening for pronunciation and comprehension practice.
Yes. Your PDF is processed on our servers for text extraction and audio generation, then available only to you. We don't share, sell, or use your documents for training. No account required means no tracking.
Up to 100MB. For very long PDFs, the system processes them chapter by chapter. Each chapter becomes a separate audio track you can play or download independently.
Yes — install the free CastReader Chrome extension. It reads PDFs open in your browser tab directly, with paragraph highlighting and speed control. No downloading, no uploading. Perfect for academic databases, arXiv, government sites, and any PDF you view in Chrome.
Yes. CastReader is a free online PDF to MP3 converter — upload your PDF, it extracts the text, converts it to natural AI speech, and lets you download each chapter as an MP3 file. No signup, no watermark, no daily limit. Most PDFs convert in under 30 seconds. Works with multi-column layouts, textbooks, and scanned documents.
If you can open and view the PDF (i.e., you know the password), the text extraction will work after you unlock it. Fully encrypted PDFs that you cannot open are not supported — you need access to the content for any converter to work.
PDF not converting correctly? Send it to our debug team
Read any PDF aloud directly in Chrome — no download needed
Convert EPUB, DOCX, and other documents to audio
Convert any text to natural AI speech — no signup, no limits
70,000+ public domain books you can listen to for free
The only TTS that works on Kindle Cloud Reader
How dual-channel reading helps — tools and techniques
Download the CastReader app to listen to your uploaded documents anywhere.
Hard numbers — not vibes — from authoritative sources
$2.22 billion
US audiobook sales in 2024, up 13% year-over-year (Publishers Weekly / Audio Publishers Association)
Source →51%
of US adults have listened to an audiobook in 2025 — roughly 134 million people (APA Consumer Survey 2025)
Source →2.2 billion
people globally with near- or far-vision impairment (WHO Fact Sheet, 2024). TTS is the primary access path for digital reading content.
Source →78%
of audiobook listeners multitask while listening — commute, chores, exercise (Audiolibrix Great Audiobook Survey, 2024)
Source →27.2 minutes
average single-trip US commute in 2024, up from 26.8 (US Census ACS via Statista). That's nearly an hour each day of audio-only time.
Source →effect size 0.35
measured comprehension lift from TTS for reading-disabled students across 22 studies (Wood, Moxley, Tighe & Wagner, Journal of Learning Disabilities, 2018)
Source →15.5 million
US adults with ADHD per CDC 2024 — about half diagnosed in adulthood (CDC MMWR, October 2024)
Source →Every Chrome Web Store review below is verifiable at the link in each card. We don't hide negative feedback — we answer it within 24 hours.
“This is 1 of the best TTS and its smooth. If this is truly free i'll keep this 100%. Every other TTS says its free but has a secret. They interrupt or they just say better ai voices pay. But i like this voice. I've tried loads and this is 1 of the best ones that actually says free.”
“Works perfectly on vivaldi. One suggestion though. I wish it had a play button appear next to a paragraph when we hover over it. Just like in the case of speechify.”
“Extremely user friendly short keys. Placed forward backward and speed up down as Natural as it could be. Voices are great and smooth. I would recommend it over many hyped products.”
“At the very least it's better than many paid TTS models. Still not as good as ElevenReader or LAP, but maybe the best free model for TTS.”
“So glad I can finally switch voices! The default was fine but I found one I actually enjoy listening to for hours. Small thing, huge difference.”
“Best one i found, user friendly, and great voice over.”
“ChatGPT's long answers are finally listenable. Let it generate while I listen — doubles my productivity. Love the inline button next to each response.”
“I tried using this add-on to listen to an ebook on the O'Reilly learning platform, and it works smoothly. However, it always restarts from the first paragraph whenever I scroll or select a different paragraph. Please consider adding a bookmark or checkpoint feature so users can mark where the reading should begin.”
↪ Founder reply
Replied by CastReader founder Yan Xu within 48 hours: acknowledged the issue, shipped a bookmark feature in the following release. Reviewer's verbatim feedback drove the v1.2 roadmap.
“Need to highlight text and select it.”
“Hard to select text.”
↪ Founder reply
Replied by CastReader founder Yan Xu within 24 hours: apologized, asked which site/browser the issue occurred on, provided a workaround using the keyboard shortcut, and offered direct support at support@castreader.ai.
We re-test, re-write, and ship continuously. Every entry has a real date.
Rewrote landing pages with verbatim Chrome Web Store testimonials, real audiobook market data, and tested-12-extensions methodology. Every claim now has a sourceable link.
Telegram audio streaming now auto-turns pages reliably across Kindle Cloud Reader and Apple Books. Reduces session interruptions by ~70% in internal testing.
Wrote up the OCR pipeline: how CastReader handles Amazon's 184 random font alphabets and 361 unique glyphs per Kindle book. Shared in dev.to.
Native macOS app reads Kindle for Mac with word-level highlighting. Floating player + system-wide hotkeys. No browser needed.
Ranked #10 in Daily, 99 upvotes, 4 community comments shaped the v1.2 roadmap.
Switched from older TTS engines to Kokoro neural voices. User reviews shifted from 'usable but robotic' to 'enjoy listening for hours' (verbatim from review by patrick chiang).
OCR success rate improved from 78% to 89% on English-language Kindle books. Multi-column page detection added for academic PDFs.
I built CastReader because I owned hundreds of Kindle books and couldn't listen to them on my morning runs without buying separate Audible copies. The technical problem — Amazon's Cloud Reader font encryption — turned out to be solvable with OCR. The product problem — making it actually pleasant across phones, desktops, and 40+ languages — took two years of iteration. We're a small team. I answer every Chrome Web Store review personally (see testimonials above — including the 3-star and 1-star ones). If something's broken or missing, email support@castreader.ai.
— Yan Xu, founder
Last reviewed: · CastReader Team — reviewed against 2025 testing data
Free CastReader works on Chrome / Edge / iOS / Android / Mac. Read any PDF aloud, on any platform.
★★★★★ 4.7 · Free · No login · No limits