NaturalReader charges $99 for premium voices and limits free users to 20 min/day. CastReader gives you natural AI voices, real-time paragraph highlighting, Kindle Cloud Reader support, and 40+ languages — completely free, forever. No account needed.
Side-by-side: what you get for $0 vs $99/year
Free Forever
NaturalReader's free tier limits you to 20 minutes per day. Premium costs $99/year. CastReader is 100% free — unlimited usage, all voices, all languages, no account required. Not a trial. Not a freemium trap.
Better Extraction
NaturalReader struggles with Kindle Cloud Reader, WeRead, Notion, and Google Docs. CastReader has dedicated extractors for 15+ platforms — handling canvas rendering, font encryption, and complex DOM structures.
Real-Time Highlighting
NaturalReader highlights sentence by sentence. CastReader highlights at paragraph level with automatic scrolling — click any paragraph to jump there instantly. Follow along naturally as you listen.
Switching from NaturalReader to CastReader
No catch. CastReader uses the open-source Kokoro TTS model. There's no API cost, so there's no reason to charge. Unlimited usage, all features, forever free.
CastReader uses the Kokoro TTS model which produces natural, expressive voices in 40+ languages. Many users find it comparable to NaturalReader's premium voices. Try it yourself — it's free.
Currently CastReader is a Chrome/Edge browser extension. It works on any web page you open in the browser, including PDFs, Google Docs, and Kindle Cloud Reader.
CastReader works differently — it reads web pages directly rather than uploading files. Open any page or document in your browser, click the extension icon, and it starts reading. For PDFs, just open them in Chrome.
CastReader requires an internet connection for voice generation. The text extraction happens locally in your browser, but audio is generated server-side for the best voice quality.
CastReader works on any web page, with dedicated extractors for 15+ platforms including Kindle Cloud Reader, WeRead, Notion, Google Docs, Medium, Substack, Wikipedia, and more.
For reading web pages aloud in Chrome, CastReader has several advantages: it's 100% free with no daily limits, has smarter content extraction that skips ads and menus, and supports complex platforms like Kindle Cloud Reader that NaturalReader can't handle. NaturalReader's strength is its desktop app and document upload feature.
Yes — CastReader is the only free browser extension that supports Kindle Cloud Reader. It uses OCR technology to extract text from Kindle's image-based rendering and reads it aloud with natural AI voices and real-time highlighting.
NaturalReader ($99/year) has a better free tier than Speechify ($139/year), with 20 min/day of premium voices. Speechify has slightly better voice quality at the premium level. CastReader is better than both for web reading — it's completely free, has no daily limit, and works on platforms both of them can't handle (Kindle, WeRead, Google Docs).
No. NaturalReader cannot read Kindle Cloud Reader because Amazon encrypts text using custom fonts. CastReader is the only browser extension that solves this — it uses local OCR to decode Kindle's encrypted text and reads books aloud with auto page-turning.
NaturalReader's free tier gives you 20 minutes per day of premium AI voices, with limited voice selection. After 20 minutes, you're restricted to low-quality system voices. Premium costs $99.50/year for unlimited usage. CastReader has no such limits — all voices, all languages, unlimited usage, forever free.
NaturalReader supports about 20 languages. CastReader supports 40+ languages including Hindi, Arabic, Portuguese, Japanese, and Korean. All languages are available for free with no restrictions.
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
Completely free. No signup. No limits. Install and start listening.
★★★★★ 4.7 · Free · No login · No limits