"Stop getting pushed to upgrade by Quizlet": how a Vietnamese dev's free flashcard app sold AI speaking into the education Top Grossing chart

OpenQuiz is a vocab app with AI speaking practice, built by a solo developer in Vietnam. The playbook is simple: give away free what Quizlet started charging for, then add an AI speaking coach on top and charge for that layer. It first built a base of Vietnamese students on the web, only reached Google Play at the end of July this year, and has racked up 114k installs in just over three months. The iOS version charted at 13 to 24 on Vietnam's education Top Grossing chart, so people are clearly paying. This piece covers how it got going, where the money comes from, what users are complaining about, and whether the playbook works in another country.

One 26-second video, 9.26M views

On Jul 11, 2026, a Vietnamese TikTok account, xuongngonngu, posted a 26-second video with one line of caption: "Hãy tải ngay Openquiz🔥🔥🔥" (Download OpenQuiz now). By November the video had 9.26M views and 180k likes.

The top comment was "can it cure laziness about studying" with 1,200 likes. The second most liked: "Scrolling TikTok, someone keeps telling you to use OpenQuiz, but nobody says how exactly to study with it." Further down, someone asked "is there Thai?" and another complained: "Just scrolled for a bit and it wants money, does anyone know how to use it for free 😭".

These comments capture the whole product: traffic from short video, selling "free," users hitting the paywall once they arrive, and people in neighboring countries wanting one too.

What it is

The store listing is "OpenQuiz - AI Flashcards." The developer, Phan Nguyễn Đức Hiếu, is Vietnamese and has registered the company CÔNG TY TNHH OPENQUIZ. The product is two things joined together:

• The Quizlet part: build your own word sets, or snap a photo of a textbook page to generate flashcards; includes dictation, quizzes and matching. Free.
• The AI speaking part: talk with an AI using words you just studied, get pronunciation scores and grammar corrections; also includes spaced repetition, an IELTS speaking mock examiner and an AI study path. This layer is paid. On iOS it's listed at $7.98 a month or $52.98 a year; on Google Play in-app purchases run $5.99–29.99.

Study paths are split by exam: IELTS, TOEIC, HSK, JLPT, TOPIK. Demand from Vietnamese learners of Korean and Chinese is strong, and the big overseas AI speaking apps mostly skip this. Web, iOS and Android sync progress across all three, and there's a Chrome extension that shows subtitles on YouTube and Netflix for shadowing, 30k users.

Metric

• Google Play: listed 2026-07-26, 11-06 installs 113,680 times, up 7,460 times in the last 7 days. August averaged about 1,700 a day, right before Vietnam's school year started; September dropped to about 1,100 a day, and from October onward it's 800–1,000 a day (third-party estimate). Declining steadily, but not dead.
• Google Play charts: only charted on Vietnam's education free chart, between ranks 27–43 from 10-29 to 11-06; Quizlet was #45.
• iOS: listed 2026-05-25; 3,268 ratings in the Vietnam store, 4.68 stars (11-06). Ranked 13–24 on Vietnam's education Top Grossing chart from 10-28 to 11-06; on the same chart Quizlet was #8, local AI speaking app Hala #6, and ELSA #5.
• Self-reported on the website: 1M learners, 120k monthly actives, users have spoken 100M sentences. None of this is verified.

Revenue isn't public. The only visible signal is iOS Top Grossing rank, which shows people are paying, but not how much.

Why now: the gap Quizlet's paywall left

Vietnamese students used Quizlet for years. Then Quizlet put the "learn" and "test" modes behind a paid tier, so students either paid or waited for a teacher to set up a class before they could use them for free. Many started looking for "free Quizlet."

OpenQuiz has pitched itself exactly that way from the start; its Facebook page bio reads "Free Quizlet Alternative." The TikTok promo copy is more direct: "Hết lo Quizlet bắt nâng cấp" (No more getting pushed to upgrade by Quizlet). In 2026 April 10, a long post in a Vietnamese Facebook group for 30+ women learning English said the writer had switched from Quizlet to OpenQuiz and bought a year's membership.

So what draws people in is "free," not AI. AI speaking isn't new in Vietnam; Hala, ELSA, Praktika and Learna all operate there, and all rank higher on the charts. OpenQuiz's approach is to use free flashcards to pull Quizlet's users over, then sell AI speaking to some of them.

Where users come from

Web first, app second. The web version was live by 2025 December at the latest, more than 7 months before the Android app. In its first week on Android it saw 1,300–1,500 installs a day, a rare start for a new package name, which suggests existing web users moving to phones (inference).

Mini accounts on TikTok and Threads. Search openquiz on TikTok and you'll find dozens of Vietnamese mini accounts, each with a few hundred to a few thousand followers. Spot-checking a few of them, 9 to 10 of their last 10 posts were about OpenQuiz. The playbook is always the same: screenshot a Threads recommendation post, add a screen recording of the app, caption it "Web này đỉnh" (this site is amazing) or "Web này xứng đáng viral hơn" (this site deserves to blow up more). Some accounts are literally named "1trieuusers" (one million users), which looks like official, or outsourced, management (my inference). Most videos only get a few thousand views, then one blows up every so often: the Jul 11 one hit 9.26M, an Aug 11 post from a different account hit 1.48M, and an Oct 27 one hit 476k.

Vietnamese-language SEO. The website has Vietnamese landing pages like "free vocab study website" and "free English study website," with titles such as "2026's best free vocabulary website for Vietnamese people."

Teacher-created classes. The app supports teachers creating classes and assigning homework, and the site claims it's "recommended by thousands of teachers." This copies Quizlet's playbook, using teachers to bring whole classes in. How many classes actually exist is unverified.

We found no evidence of paid ads, but that can't be ruled out. There's no press coverage and no one is discussing it on X. The whole thing seems to spread mostly within Vietnamese student circles.

What users are complaining about

Reviews on the iOS Vietnam store from 8 to November: the praise and the complaints are about the same thing, the paywall:

"Can't get past lesson two, it keeps asking me to buy premium." (2 stars, 10-01)

"The app is dull, has bugs, won't let me review words, and wants me to buy premium just to review?" (1 stars, 09-28)

"Everything needs payment. ELSA only charges for advanced features, because those cost bandwidth; basics should be free so people build the habit first." (2 stars, 09-01)

"Paid and got charged, still can't get in, it keeps asking me to sign up." (1 stars, 09-29)

Another common complaint is crashing after updates: in early October there were several reviews saying "crashes right after update" and "I already paid for VIP and it still does this, how am I supposed to study."

Some users defend it: "The free version is enough, pay if you want more. If you want everything free, delete the app and stop complaining." (5 stars, 10-03) One high school student wrote: "Found it through TikTok, it even has materials for the new textbook, if you can afford it just buy premium." (5 stars, 09-11)

So "the free Quizlet" doesn't quite match what users actually run into: spaced repetition and speaking practice sit behind the paywall, and plenty of people came for "free" and hit the wall after ten minutes. That gap pushed it up the bestseller charts and also brought it one-star reviews.

Who it's competing with

No obvious copycats seen. The Vietnam slot is already crowded: Luyện Từ for flashcards, Hala and ELSA for AI speaking, and OpenQuiz itself is moving into Taiwan (its iOS Taiwan version is called 「背單字·練口說」).

If it were you

Verdict: worth following, but don't enter through Vietnam. Copy the playbook: find a tool local students already use that has just started charging, give away the paid parts for free, then sell AI speaking on top. Build a website first to capture search traffic, then ship an app. Vietnam is already taken by it and local rivals, but neighboring countries are still open, and comment sections already have people asking "is there Thai?"

Who it suits: 1–2 people whose native language is Thai, Indonesian, Filipino, Turkish or similar, who are or recently were exam students themselves and know what local students study for and which group chats they talk in; can build a website, integrate a voice API, and is willing to film short videos every day.

Who it doesn't suit: anyone wanting the English-learning market (Quizlet, Knowt, Anki plus a pile of AI speaking apps, already packed); anyone who only wants to build an app and not a website or SEO (OpenQuiz launched with a batch of existing web users, and a bare new package name doesn't get that head start); anyone unwilling to make short videos.

How to do it:

• First check what students in the target country use. Is Quizlet the main tool? Since study and test modes went paid, are people in local forums or on TikTok looking for a "free Quizlet"? This takes a day and is the premise for everything else.
• Launch the website first: create word sets, generate flashcards from photos, free quizzes across the board, and learning paths built around national exams (Thailand: TCAS and TGAT; Indonesia: UTBK; plus English, Japanese, Korean and Chinese proficiency tests).
• Put the paid tier on AI speaking, pronunciation scoring and exam simulations. Don't lock spaced repetition: most of OpenQuiz's bad reviews say "even review costs money" and "the free version hits the wall in ten minutes". That is its weakest point and the easiest to beat.
• Build the mobile app once the website has stable daily active users, with progress synced across three platforms.

How to get users: copy OpenQuiz's approach and run 5–10 short-video accounts, each talking about only this one product. The material is "screenshot a recommendation post from Threads or X + a screen recording of how it works", with the first line saying "free" and "no more being pushed to upgrade by Quizlet". Turn comments asking "how exactly do I study?" into the next video. On the website, build landing pages in the local language such as "free vocabulary website" and "free English learning website". Add a teacher class-creation feature and get a few tutors to use it first.

When to start: peak season for Southeast Asian students is before the school term and before exams. Thailand and Indonesia's major exams cluster from early to mid-year, so ideally get the website and the first batch of video accounts running before February 2027.

Signs you've misread it: (1) the target country's students mainly use something other than Quizlet, or nobody is searching for "free Quizlet", so there's no gap to exploit; (2) two months after launch, daily active users from search and short video are still only in the low hundreds, meaning the "free" hook isn't strong enough locally; (3) OpenQuiz itself launches a localized version in that country and starts filling it with videos (it is already doing this in Taiwan); (4) Quizlet makes study and test modes free again.