CastReader
CastReader
CastReader is a Chrome and Edge extension (with iPhone and Android apps) that reads webpages, PDFs, Google Docs, and Kindle books aloud with word-synced highlighting and auto-scroll. When a passage is dense, the AI-powered Read & Explain annotates the original page and talks you through it instead of replacing the text with a summary. Nine languages are auto-detected, and it starts free with no signup: 20 minutes of read-aloud and three explanations a day. The one job it does better than everyone is Kindle. Amazon's Cloud Reader scrambles font mappings, so the well-known text-to-speech extensions — Speechify, NaturalReader, Read Aloud — extract gibberish and fail. CastReader runs tesseract OCR locally in your browser on the visibly rendered page, recovers the text with word-level bounding boxes, highlights each word as it speaks, and turns the pages automatically. It does not download, decrypt, or redistribute book files — it reads what is already visible on your own signed-in screen.
Keywords
text-to-speech, kindle, read-aloud, ocr, browser-extension
- Works on Kindle Cloud Reader: local tesseract OCR reads the rendered page, bypassing the font scrambling that breaks every mainstream TTS extension.
- Word-synced highlighting with auto-scroll: follow the text as it speaks, click a paragraph to jump there, auto-advance chapter by chapter.
- Read & Explain on the original page: difficult passages get annotated in place, in your language, with pointers back to the source text.
- Free to try without an account: 20 minutes of read-aloud and 3 explains per day; site-specific extractors for Notion, Google Docs, arXiv, Substack, ChatGPT, and more.
TMRW VERDICT
The read-aloud that survives Kindle's font scrambling
by TMRW Team·Aug 31, 2026
Read-aloud extensions are a crowded, mostly interchangeable category, and a directory has no business listing another one. CastReader is here for a single verifiable reason: it works on Kindle Cloud Reader, where the big names fail, and it explains exactly how — local OCR on the rendered page with word-level bounding boxes — instead of hand-waving about AI. When a product in a commodity category can name the mechanism behind its one hard claim, that is worth a card.
The approach has honest edges, and the site names them: extraction depends on the current Cloud Reader layout, publishers control some text-to-speech permissions, and the OCR reads only what is visibly rendered on your own signed-in account. If your relationship with Amazon's terms of service is cautious, read their FAQ before a long session. If you mostly want audiobooks, this is not that product — Audible performances and OCR-fed synthetic voices are different things, and pretending otherwise sells both short.
Skip it if you just want articles read aloud: Edge has a built-in reader, and every competitor handles ordinary webpages fine. The reason to install this one is a Kindle library you want to hear on your laptop or phone, or the Read & Explain flow for dense material in a second language — the German support is unusually complete, covering voices, interface, and Kindle OCR.
No stars until we have listened through a real book chapter by chapter, because the whole product stands on whether the OCR and auto-page-turn survive an hour of continuous use, and that cannot be judged from a landing page. The free tier requires no account and covers exactly that test. Run it on one chapter of your own library before paying for anything.