Read Preview Aloud — Hear Any PDF on Your Mac
Select any text in macOS Preview — an arXiv paper, a legal contract, a technical whitepaper, a scanned report. A floating ▶ appears next to your selection. One click — natural voice plays with word-level highlight on the real Preview window. Uses Apple's native Accessibility path — no Screen Recording permission required.
macOS native · Free · No login · 40+ languages · Native AX, no OCR
We propose a novel attention mechanism that scales sub-quadratically with sequence length while retaining expressive capacity comparable to full self-attention. Our evaluation across four language-modeling benchmarks shows consistent improvements at long contexts, with negligible overhead at short lengths.
Highlight follows each spoken word directly inside your Preview window.
One App Covers Every Mac PDF & Research Reader
Same gesture, same word-level highlight — across every native PDF app researchers and students actually use.
Preview
Apple's PDF viewer
PDFgear
Free PDFKit reader
Adobe Acrobat Reader
Industry standard
Skim
Academic favorite
PDF Expert
Readdle paid PDF
Three Steps — Native, No OCR
Preview is a native AppKit app and exposes its PDF text through macOS Accessibility. CastReader reads it directly — no screen capture, no OCR, pixel-perfect highlight.
Install
Download CastReader for Mac (.dmg). Grant Accessibility permission once. Preview doesn't need Screen Recording permission.
Select
Open any PDF in Preview. Drag-select the paragraph you want to hear — a paper abstract, a legal clause, a method section.
Click ▶
A play button appears next to your selection. One click — audio starts and the highlight glides inside the actual Preview window, word by word.
When Researchers Add Read-Aloud to Preview
Preview is where academic and professional readers spend hours every day. Papers, contracts, reports, whitepapers — dense prose that destroys your eyes if you read all of it on screen.
Listen to paper abstracts and intros
The first page of every arXiv / PubMed / bioRxiv PDF is dense prose. Listen while your eyes scan figures — triage 5× faster.
Hear method and result sections
The middle of a paper is where comprehension matters most. Audio at 1× forces engagement; 1.5× speeds triage without losing structure.
Proof-listen your own draft
Export your own manuscript to PDF, open in Preview, listen. Hearing your prose catches awkward phrasing that eyes skim past.
Study long legal contracts
Contracts, terms of service, policy documents — long dense prose. Listening at 0.9× gives you time to catch asymmetric clauses.
Read foreign-language PDFs
CastReader auto-detects the language — Japanese whitepapers, Chinese reports, German contracts — and uses the native voice for each selection.
Accessibility for dyslexia and long-session fatigue
Hours of PDF reading strain the eyes and brain regardless. A listening channel halves fatigue — the same logic as dual monitors.
Why Native AX Makes Preview the Cleanest PDF Surface
macOS Preview exposes its PDF text through the Accessibility API, the same way Xcode and TextEdit do. That means no Screen Recording permission, no OCR latency, perfect character alignment.
Pixel-perfect highlight on the real document
Because text comes through AX, the highlight overlay lands exactly on each character of the rendered PDF page — no OCR drift.
Works with every PDF — text, scans, even mixed
If Preview can select the text, CastReader can read it. For image-only scans, Preview's built-in OCR runs first — then audio works on the recognized text.
40+ natural voices, CJK and multilingual aware
Chinese abstracts, Japanese whitepapers, Spanish legal text — auto-detected and read with native voices. Kokoro-quality audio, not system say.
Zero cost, zero signup
No account, no credit card, no premium voice gate, no daily word limit. Free forever — the missing TTS Preview should have had.
Common Questions
How do I read a PDF aloud in Preview on Mac?▾
Install CastReader for Mac (.dmg), grant Accessibility permission, open any PDF in Preview, drag-select the paragraph you want to hear, and click the floating ▶. Word-level highlight appears on your real Preview window.
Does Preview have built-in text-to-speech?▾
macOS has a system-wide Speak Selection (Edit → Speech → Start Speaking) but it uses old Siri voices, gives no visual highlight, and can't resume mid-paragraph. CastReader adds Kokoro-quality voices, word-level highlight on the real Preview window, variable speed, and click-to-jump — everything the built-in lacks.
Will it work on scanned PDFs without a text layer?▾
If Preview can select the text (via its built-in OCR on images), CastReader reads it. For pure image PDFs with no text layer at all, use Preview's Tools → Text Recognition first — then CastReader picks up the recognized selection.
Does Preview need Screen Recording permission?▾
No. Preview is a native AppKit app and exposes PDF text through macOS Accessibility APIs. Only Accessibility permission is required. That's why Preview is one of the cleanest read-aloud surfaces on Mac.
Can I listen to Chinese, Japanese, or Spanish PDFs?▾
Yes. CastReader auto-detects CJK and European languages and switches to native voices. Mixed-language selections (e.g., a paper with English abstract + Chinese discussion) switch voice at sentence boundaries.
Does it work with arXiv / PubMed / bioRxiv papers?▾
Yes — once you download the PDF and open it in Preview, any selection reads aloud. For the web reading view of those sites, see our dedicated pages: arXiv listen, PubMed listen, bioRxiv listen.
What about multi-column academic papers?▾
Preview's column detection works well when you drag-select the column you care about. CastReader reads the selected text in order. For very dense two-column layouts, select one column at a time for cleaner reading flow.
Does it handle math notation and formulas?▾
CastReader reads the literal characters of your selection. Inline LaTeX or plain-text math is spoken as characters. For rendered equation images, Preview's OCR doesn't pick them up — select the surrounding prose instead.
Is it really free?▾
Yes. 100% free — no account, no credit card, no premium voice gate, no daily word limit. Download the .dmg and use it forever across every supported Mac app.
Ready to Hear Your PDFs Speak?
Install once. Open any PDF in Preview. Select a paragraph. Click ▶. Listen.