Substack has its own read-aloud, but only in the Substack app — the website has none at all. This page says which route applies to the post in front of you, and what to do when Substack's own audio is not there.
Substack does have text-to-speech, but with three limits: it exists only in the Substack mobile app, only for posts written in English, and only on most — not all — publications. Writers cannot switch it on for their own publication, and Substack does not publish the rollout criteria. On the Substack website there is no read-aloud at all. So on desktop, or when a publication has not been given automatic narration, open the full post in Chrome or Edge and press CastReader, which reads the visible article body with paragraph highlighting. If the author recorded their own voiceover, that track is usually the better listen. For paid posts, sign in with your own subscription first — CastReader reads text already visible to you and does not unlock or bypass a paywall.
Substack's own audio covers some posts and not others. Find your case before installing anything.
The publication has automatic narration. Tap play at the top right of the post — six built-in voices, nothing to install. This is the simplest route when it is available.
Other reading routesSome writers publish their own narration, or syndicate it to a podcast feed. Use that track — it carries the author's own emphasis and edits, which no synthetic voice reproduces.
When text is betterThe Substack site has no read-aloud, on desktop or mobile browser. Open the full post in Chrome or Edge and press CastReader to hear the article body with the current paragraph highlighted.
Read any page aloudSign in with the subscription you own and open the full post first. A reader can speak what the page already shows you; it cannot fetch paragraphs the publisher is withholding.
See what is freeSubstack's own narration, author voiceovers, text-only posts, paid posts, and custom domains each need a different answer.
Automatic AI narration with six voices exists in the Substack mobile app, for English posts, on most but not all publications. Writers cannot enable it themselves and the rollout criteria are not public. Open the same post in a browser and there is no play button at all — that gap is what a browser reader fills.
Some authors publish an audio version or podcast episode with the post. Use that track when it is available because it may include the author's own narration, edits, or production choices.
On a standard Substack /p/ page, CastReader targets the readable post body and leaves subscription widgets, comments, navigation, and most page controls out of the listening queue.
Open the post while signed in to the account that owns the subscription. CastReader can read content rendered in the tab, but it does not fetch hidden paragraphs or circumvent the publisher's access rules.
A publication using its own domain may customize the page structure. Start playback and check the first two paragraphs; if navigation or unrelated text enters the queue, select the article passage you want instead.
A Substack post page is the essay plus a lot of things that are not the essay.
| What you're reading | What the page reader does | If it sounds wrong |
|---|---|---|
| The post body on the web | Reads the essay text | Nothing needed |
| A post you only partly have access to | Reads what the page actually shows you | Subscribe if you want the rest; nothing is worked around |
| Subscribe boxes and share buttons between sections | Are page furniture and may be read in sequence | Select the essay text instead |
| Footnotes | Sit apart from the paragraph that references them | Read the footnote separately when you reach the marker |
| Embedded audio or video | Is a player, not text | Use the publication's own player for that |
| The comment thread | Is below the post body | Select the comments you want spoken |
Follow the newsletter link to the publication page and wait for the article body to load. Email previews and Substack feed cards may contain only an excerpt.
If the post already includes audio, use it when you want the author's intended narration. Continue with CastReader when the post is text-only or you prefer a different speed or voice.
The reader builds a queue from the visible article body and follows it with paragraph highlighting and playback controls.
Expand any collapsed section, reload after signing in, or select a specific passage when a custom theme, embed, or paywall transition changes the page structure.
The confusing part is that Substack both does and does not read posts aloud. It added automatic narration — six synthetic voices, generated without the writer doing anything — but shipped it only inside the mobile app, only for English posts, and only to a subset of publications. Writers cannot request it, and the criteria have never been published. So two newsletters in the same inbox can behave differently, and the same post that plays on your phone has no play button at all when you open it on a laptop.
That asymmetry is worth naming plainly, because most pages on this subject either claim Substack has no text-to-speech or imply it works everywhere. Neither is true. If the play button is there, use it — it costs nothing and nothing needs installing. The question this page answers is what to do in the other cases: on the web, on a publication that was skipped, or on a post in another language.
A Substack email, feed preview, and full publication page are not the same reading surface. The email may contain an excerpt, while the complete post lives on the publication site. For reliable text-to-speech, open the full post first and confirm that the paragraphs you expect are actually visible.
Audio availability is set by each publication. Some posts include the author's own audio, some link to a podcast episode, and many are text-only. A useful read-aloud workflow should not pretend those cases are identical: use native audio when it exists, and use a browser reader for visible text when it does not.
Access rules still apply. Reading software can speak content you are authorized to view, but it should not bypass a paid subscription, copy hidden text, or claim access to an author's full archive. Custom domains and embedded media can also change extraction quality, so check the opening paragraphs before starting a long listening session.
Answers for native audio, paid newsletters, custom domains, comments, and mobile use.
Yes, with limits. Substack generates automatic narration with six built-in voices, but only inside the Substack mobile app, only for posts written in English, and only on most publications rather than all of them. Writers cannot turn it on for their own publication and Substack has not published the rollout criteria. On the Substack website there is no read-aloud at all.
Yes, by one of three routes: Substack's own narration if you are in the app and that publication has it; the author's recorded voiceover if they published one; or a browser reader such as CastReader on the full post, which is the only route that works on the website.
It is the play button at the top right of a post in the Substack mobile app. If you do not see it, that publication has not been given automatic narration — it is not a setting you or the writer can switch on.
The Substack website has no read-aloud of its own, so it takes a browser reader. Open the full post in Chrome or Edge, press CastReader, and check that the first paragraph matches the article before settling in.
Open the full post in Chrome or Edge. If the author did not include native audio, press CastReader and verify that the first paragraph matches the article before continuing.
Use the author's audio when you want the original narration or produced podcast version. Use CastReader for text-only posts, a different playback speed, or paragraph highlighting while you follow the written article.
Yes, when you are signed in and the paid text is already visible in your browser. CastReader does not unlock hidden content or bypass a publication's paywall.
You may be on an email preview, feed card, or paywall excerpt instead of the full post. Open the publication page and sign in with the subscribed account before starting playback.
The standard article workflow focuses on the post body and excludes the comments section. If you want to hear one comment, expand it, select its text, and use selected-text reading.
Often, but custom themes can change the page structure. Check the first paragraphs after starting; if unrelated page text appears, select the article section you want to hear.
If that publication has automatic narration, yes — tap play at the top right of the post; that is Substack's own feature and needs nothing else. When the play button is absent, the post is not in English, or you would rather use a different voice or speed, CastReader has iPhone, iPad and Android apps alongside the desktop Chrome and Edge extension.
Automatic narration is rolled out per publication by Substack, not chosen by the writer. Two newsletters you subscribe to can differ for no reason you can see or change, which is why a browser reader is the dependable route when you want every post to be listenable.
CastReader is free to start with daily allowances. Pro provides higher usage limits and additional voice and explanation access; see the pricing page for current limits.
From our own read-aloud report — 41,396 anonymous listening sessions across 3,075 devices, 8 April to 22 June 2026. A behavioural sample of CastReader users, not a census of all readers.
Read the full reportDownload the CastReader app for DRM-free EPUB import and supported mobile reading workflows.
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.
CastReader provides native apps for iPhone and Android; Android downloads are available directly from Google Play.
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.
The phone app flow now has its own landing page for bookshelf sync, Read Aloud, synced highlighting, auto-scroll, background playback, and resume progress.
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 9 supported 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
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