A Vietnamese vocab site switched languages and installs tripled in a week: VocaPy's play was "free, made by Vietnamese people, better than Anki"

VocaPy is a vocab app Vietnamese learners use for Chinese, Japanese and Korean. The web version launched first, and the mobile app came out at the end of September. In the first week of early November, its Google Play installs rose from 1,304 to 4,437, and its rank on the Vietnam Education free chart jumped from #142 to #56. It shows no sign of paid advertising and has no unique technical features. A small Vietnamese team copied its English vocab website almost as is, swapped in Chinese, Japanese and Korean content, and pushed it through a steady drip of study-account posts on Threads. Below: how it took off, how it makes money, and whether the play can travel to other countries.

"DAY 37" on Threads

On May 4, 2026, a Threads account called @hoctienganhfree ("Learn English for Free", 14K followers) posted something that opened with "DAY 37: I learned it so you don't have to struggle so hard 🥺🥺🥺":

"After a month offline, I've finally finished the Chinese website: HSK 1–6 vocabulary, HSK textbooks, BOYA, common radicals, D04 compound words, 3.0, specialist vocabulary, everyday phrases... Come in and study, and climb the leaderboard. The site is called vocapy dot com."

The author added a comment below: "The site has daily streak 🔥, leaderboards, and adds words faster than Quizlet and Anki. It's free. Students, or anyone who just wants to try it, DM me and I'll give you Pro for free." The post has now reached 26.5k views. Someone in the comments asked "Does it cost money?" and another asked "I know nothing, can I learn?" The author replied: "I know nothing either. I built this site to teach myself."

This account used to teach English and pushed the team's English vocab site, Luyện Từ. A few days earlier, the official VocaPy account @vocapy_com had posted an introduction: "A vocab site specializing in logographic scripts, with Chinese, Japanese and Korean". It got 1,600 likes and 10.8k views, and a co-founder personally answered questions about features and the free tier in the replies (Threads, 05-01).

Half a year later, in early November, someone on Threads asked a single question that got 804 likes: "Which app shows vocab words on the lock screen?" Someone followed up, "Does it have Japanese kanji?", and the reply was: "Yes, Chinese, Japanese and Korean are all there. The app is Vocapy." (Threads, early November.) The same week, VocaPy's Play installs rose by over two thousand.

What it is

A vocab tool for Vietnamese learners of Chinese, Japanese and Korean. You build your own word lists or pick a ready-made exam track: HSK 1–6 and HSK 3.0 for Chinese, TOCFL for traditional characters, JLPT for Japanese, TOPIK for Korean. Review runs on spaced repetition (SRS), so words you're about to forget come back automatically. The Play store page says "9 kinds of practice, not just flashcards": multiple choice, typing, matching, listening, sentence building, stroke-order handwriting, plus a Flappy-style reflex game. There are also leaderboards, a coin shop, classes (teachers assign homework), and "shared streaks": invite a friend to keep a daily learning streak together, and if either of you misses a day, both streaks reset.

The web app vocapy.com is the main stage. It launched in 2026, and in May 4 it had over 500 dictation lessons and 100 mock exams. The app went live on Play in September 26 and on iOS in September 30. The store pages keep stressing "same account as vocapy.com: study on your computer, and your progress is there when you open the phone app."

The team is based in Vietnam. The Play developer name is Trương Đức and the iOS developer name is Hieu Nguyen. The support email on the Play page is [email protected], which is Luyện Từ customer support. Luyện Từ is the English vocab product they built first. It has 51k installs on Google Play (Google Play, 11-06), and its website structure, copy and features are nearly identical to VocaPy's. VocaPy is essentially the Chinese, Japanese and Korean version of Luyện Từ.

How big it is

The pond is small: a few thousand installs, and it only ranks in Vietnam. The iOS app updates often: from late September to early November it shipped 25 versions, and from late October it was nearly one release a day. The 11-04 version added a home-screen widget (AppInsider).

The rating drop came from a bug. Oct 31, installs had just started climbing, and a few bad reviews hit the store page: "Just downloaded it, logged in, and got kicked back to the home page. Deleted and reinstalled, still doesn't work" and "keeps crashing" (Google Play, 10-31). The developer replied to all of them on Nov 3 with the same line: "Please update to the latest version, our team has already fixed it :(( We'd really appreciate it if you could re-rate us, thank you". The rating fell from 4.6 to 3.2, right as the new users were pouring in.

Where users came from: a ring of study accounts on Threads

VocaPy is barely posted about on TikTok (the official account has 32 followers and 3 videos), nobody mentions it on X, no media has covered it, and I couldn't find any ads. Its users come almost entirely from the Vietnamese Threads circle of Chinese learners, and the pitch comes down to three lines: free, made by Vietnamese people, better than Anki / Quizlet.

• The official account and the founder both posted: the account's intro post for 5-01 got 10.8k views, and a co-founder answered questions in the comments one by one.
• An old account gets repurposed: @hoctienganhfree, which had a following of English learners, started pushing Luyện Từ. In May it switched to the Chinese version, using a "DAY N self-study diary" voice and offering Pro to students who DM.
• Sock puppets take over: @toofdangiu (528 followers) posted from 9 through November: "Everyone learning Chinese should know about Vocapy", "100% free", "made by Vietnamese people", and it also replied under other people's posts. The official website's homepage displays its posts as user reviews. The posts all share the same hard-sell tone: "Whoever built this free vocab site, let me bow to you 🙏🏻" and "I recommended it to 10 people learning Chinese, and they all came back to thank me."
• Capturing traffic under "recommend me an app" threads: under the post with 804 likes about the lock-screen vocab feature, two accounts both replied "Just download Luyện Từ and Vocapy", and one of them also appears in the testimonials on the official site. Outsiders can't tell whether these accounts belong to the team or are paid partners (my inference: at least one of them is).
• Build the web audience first, then move it into the app: the web version 4 was accumulating users from May, and the app arrived at the end of September to absorb them, so it had a base the moment it launched.
• Referral mechanism: the referrer gets 5% of orders that come through their referral code, and new users get 95% off. "Shared streaks" and leaderboards make people actively pull in classmates.

The jump from 10-31 to 11-03 lines up in time with the hot lock-screen-widget thread and iOS's new widget release, but there's no proof of causation.

Where the money comes from

The free tier holds 500 words and 2 AI uses per day. Pro unlocks every exam track and raises AI uses to 30 per day (the web pricing page says 100), plus an "AI-graded sentence writing" game. Prices are 3 months for 199k, 6 months for 299k, and 12 months for 499k Vietnamese dong, about $7.5–19. The pricing page shows a countdown discount ("Offer ends in 24 days").

The payment method is worth noting: on the web, Vietnamese users pay by scanning a VietQR bank transfer, and only overseas users buy through in-app purchase. The transfer route skips the store's 15–30% cut, but the cost is that this revenue is completely invisible on the store's grossing charts. VocaPy doesn't appear on any grossing chart, so nothing public shows how much it actually earns.

Who it's competing with

The market for learning Chinese, Japanese and Korean in Vietnam is far from empty. Big players have been there for a long time:

VocaPy isn't the first to do this, and it's far from the biggest. Its position: one account covers three languages (rivals are mostly one app per language), the free tier is generous, and you can use it straight from the web. No single feature is unique. Lock-screen vocab already exists in WordBit, SRS in Anki, gamification in Mochi. It wins on positioning and messaging, not technology.

XieHanzi launched a little over a month later with nearly the same positioning, which suggests a second player has spotted the same gap.

Why it could take off

1. The template is ready. The "free web vocab + Threads promotion + bank transfer for Pro + app sync" model was already tested by the team on its English version, Luyện Từ. VocaPy just swapped in different content. Neither development nor user acquisition starts from scratch.
2. Demand is hot. More Vietnamese people are learning Chinese: there are many Chinese factories and Chinese-language jobs, the gaokao has a D04 Chinese component, the new HSK 3.0 syllabus just came out, and Hanzii and Migii are both pushing 3.0 updates. Exam word lists are ready-made content.
3. The pitch lands with students. Vietnamese Threads study circles respond to "free, made by locals, better than Anki." Every promo post hits only those three points.
4. Ships fast. 6 to 25 versions a week, fixes bad reviews within two or three days and replies to each one. But the login flow wasn't tested before scaling, and the rating already took a hit.

If it were you

Short version: worth a try, but don't go head-to-head with it in Vietnam. What's worth taking is the template: a free vocab site in one native language, cloned for other languages, seeded through study-account posts on social platforms. Pick a country with no localized vocab tool yet. The weak spot is zero public evidence of revenue, and the product itself has no moat.

Who it suits: a team of 1–2 people, at least one a native speaker of the target country who is already inside its study communities (Threads, Facebook groups, TikTok study accounts) and can write in a "I'm studying this too" voice. Needs to be able to build a website plus app sync and clean up exam word lists. Examples: Thai, Indonesian or Filipino learners of Chinese, Japanese or Korean, or Vietnamese and Indonesians sitting IELTS or learning German for work in Germany. VocaPy already added Thai to its iOS interface, so a Thai version may come soon (inference).

Who it doesn't suit: anyone trying to build a second VocaPy in Vietnam: eUp, Mochi and XieHanzi are already there, and the pitch has been overused. Anyone outside the target country's study community who can only write ads in translation: this approach depends on "a local who's also learning," and outsiders can't fake that. Anyone expecting to win on features: Anki and Quizlet already have every one of them.

How to build it: start with the web, not the app. Build full, graded word lists for the target exams (HSK, JLPT, TOPIK, IELTS), add SRS, dictation, a few mini-games and leaderboards. Make the free tier generous and sell Pro as "all routes + AI sentence correction," priced at 3 / 6 / 12 months, matched to what local students can actually pay (VocaPy charges $7.5–19). Take payment with local QR-code bank transfer, and use the app only as a reminder and retention channel, launched once the web has a few thousand active users. Lock down login and sync before scaling. VocaPy's three days of crash reviews are the lesson you already have.

How to get users: follow its four-step playbook. The official account posts a sincere "who we are, why we built this, what's free" post, with the founder answering comments. Find an account already making study content and run a serialized "DAY N of self-study" diary through it. Give free Pro to students in exchange for posts. Reply daily under hot threads like "recommend a study app" and "how to memorize vocab," then pin the good threads to the website as testimonials. Referral codes with commissions and "study together" streaks get users to bring in friends.

When to move: no rush, this isn't a one-off event. But VocaPy is already expanding its interface languages (Thai added on iOS), so claiming a country early matters: launch the website within 3 months and read retention and paid conversion within six.

Signs you've misread it: ① two months after the website launches, fewer than one in ten sign-ups from seeded posts are still studying the following week, meaning free vocab doesn't retain people; ② with a few thousand active users, Pro conversion is still too low to cover server costs, meaning "free" as a selling point is scaring off paying users too; ③ a local big player like eUp or Mochi already does free vocab well in your target country; ④ VocaPy or Luyện Từ launches a version for your country first.