One person used open-source AI voices to turn "Chí Phèo" into a radio drama. The Vietnamese audiobook app Truyện Ơi hasn't broken out, but its math is worth copying

Truyện Ơi is a Vietnamese reading and audiobook app built solo by developer Ngoc Hai Huynh. It launched in Oct 2026 19. It turns 47 public-domain classics into audiobooks with “all-character AI voices + background music + sound effects,” and charges through a subscription and voiced chapter packs. In Nov 6 it appeared at #37 on Vietnam's App Store Books Top Grossing chart, which looks like a breakout but isn't. Its rating count has been stuck at 5 for 9 days. Its free chart rank dropped from #40 to #153,11-03 to #11-05, and for three days it wasn't on any chart. Below: what it does, how much that Top Grossing spot is actually worth, who's competing with it, and what you can take from it.

One middle-school textbook, two ways to listen

Open truyenoi.com and the first shelf on the homepage is "Sách mở đầu một năm" (the first books of the year). The first one is Nam Cao's "Chí Phèo", a story from the Grade 11 Vietnamese literature textbook. The full text is free to read on the web, and you can listen right in the browser.

In the app, the same book has two listening modes. "Thuyết minh" is a single AI voice reading from start to finish, running locally on the phone. Once the voice is downloaded you can listen offline, and it also works for EPUBs and PDFs users upload themselves. "Lồng tiếng" is the one it actually wants to sell: the narrator is a northern male voice, Đức Trí, or a southern male voice, Tâm Đức. Each character gets their own voice, with background music and scene-matched sound effects. It sounds like a radio drama.

The store listing says where the voices come from: the open-source Vietnamese model VieNeu-TTS, plus voices cloned from voice actors who signed written consent. The covers are all AI-generated. The library only includes three kinds of works: those whose authors and translators died 1975 or more years ago and are out of copyright under Vietnamese law, originals, and licensed works. Every book page lists the author's birth and death years, the translator, the text source (Wikisource), and the copyright basis.

One person, a bit over two weeks, and it covers iPhone, iPad, CarPlay, widgets, and foldables. 10-31 has already shipped as version 1.2.1, with the interface in English, Chinese, and Vietnamese (the Vietnam App Store page, 11-06). The product is very polished, no complaints there.

How it makes money

The last line is the most useful. AI narration costs scale with compute, so it sells by the chapter, about 1,500 to 2,000 dong per chapter (roughly 6 to 8 US cents). Turning generation cost directly into a price tag users understand is a pricing idea worth taking.

What the Top Grossing #37 is worth

Vietnam App Store charts, 10-28 to 11-06.

This is a standard new-app curve: in its first two weeks it got store exposure for new apps and reached #40 on Top Free, then declined steadily with no second wave. All 5 ratings came from the first week after launch. The two reviews visible in the store, from 10-22 and 10-23, are both five stars and generic ("App hay, dễ nghe, dễ dùng": good, easy to listen to, easy to use), likely written by friends or early testers (inferred).

It held Top Grossing #37 for only one day. The Vietnamese books Top Grossing bar is low. On the same day, Truyện Audio Full, with only 33 ratings, was #10,65, and Biboo, with 31 ratings, was also on the chart, alongside Korean 리디, Chinese 晋江, and Bilibili Comics. At that spot, a few annual subscriptions or chapter packs are enough (inferred). It shows people did pay, but in small numbers.

Where users come from: right now, almost nowhere

• Store: The curve above is all there is. Store exposure ended after launch and the rank dropped off.
• Web search: truyenoi.com has many shelf pages built around scenarios ("Winter bookshelf", "Books to read at Tết", "Books about teachers and students"), and each book has a full-text page. The direction is clear: it's aimed at students searching for textbook material. But 11-06, searching site:truyenoi.com on Brave returned zero results. The site isn't indexed yet, so SEO contributes no traffic for now (inferred).
• TikTok, X, Facebook: searching "truyện ơi" or "truyenoi" returns only other people's audio story videos. There's no official account, and I didn't find any third party mentioning it.
• App Store events: The store page has an "Events" slot, and reports say there was an event in Nov 13. I didn't read the content, and it's unverified.

The listeners it wants to win over are already listening for free on YouTube. For the same "Chí Phèo", Voiz FM and VTC Now both posted human-read versions to YouTube. A 55-minute reading on the Bắc Giang city library channel has 94k views, and there are many "truyện audio" channels. Truyện Ơi first has to pull these viewers from YouTube into the app, then get them to pay for the "AI version". Neither step has started.

Who it's competing with

Only one thing is truly unique to it: full-cast radio-drama versions of public-domain classics. The other two, seamless switching between reading and listening on the same sentence and per-book copyright labels, are well done and better than rivals, but they're not things users will pay for specifically. As for "turn any book into an audiobook with one tap", once open-source models arrived, LoHi and Voice Truyện were already doing it.

If it were you

Verdict: Copying it for Vietnam isn't worth it. It hasn't proven people will buy this, the subject matter (public-domain classics) mainly draws students and nostalgic readers with low willingness to pay, human versions are free on YouTube, and the base models are open source, with two similar products the same month. What's worth learning is the method: open-source minority-language TTS + public-domain library + selling AI narration by the chapter, which can be built with almost no spending.

Who it suits: Indie developers whose native language is a minority language (Thai, Indonesian, Tagalog, Malay, etc.) and who can judge whether the open-source TTS for that language sounds good. The prerequisite is an open-source model natural enough for that language, while the local leading audiobook apps still rely on human narration, have little content, and charge high prices.

Who it doesn't suit: Anyone who wants to go head-to-head with Fonos or Voiz FM in Vietnam. Anyone who thinks "polish" alone will bring volume: Truyện Ơi is proof that polish doesn't mean people show up. And anyone who can only build apps and can't do content distribution.

How to build it: Don't just do public-domain classics. Users pay for web novels and books they already have, so "turn your own EPUB into a multi-character audiobook" sold by the chapter is more promising than selling a classics library. Keep the classics as free content and SEO pages.

How to get users: The thing it didn't do is your opening. Cut the AI-narrated version into vertical clips of 1 to 3 minutes, one character and one scene each, post them to TikTok and YouTube Shorts, and end by pointing viewers to the app to keep listening. Build shelf and full-text pages the same way it did, but plan for months before search indexes them.

When to call it early: Don't rush. This bet is about when open-source TTS for a given language gets good enough, not about launch day. Once a language has a good open-source TTS, the window lasts a few months. In Vietnamese, three similar apps appeared between late August and late October.

What would prove I'm wrong: ① By January 2027, Truyện Ơi has passed 100 ratings in the Vietnam store, or charted in Books Top Grossing in the top 50 for 30 straight days. That would mean people really buy the "AI audio drama" version, and I'd raise the grade. ② A second ranking wave after the November 13 store event would mean store events can replace paid acquisition, which small teams can use. ③ The reverse: if simpler listen-only clones like LoHi keep growing while Truyện Ơi stays flat, users just want something that reads aloud, and voice acting and sound effects aren't worth paying for.