# [021] Niche language-learning apps that Duolingo doesn't cover (sign language, Irish, Korean TOPIK exam prep…): one person builds one language, native speakers review it, subscription. Each market is small, so you need to spread across 2–3 languages

> Source: https://stringers.io/en/o/021.html (Stringers / 什么值得做, generated 2026-11-08)
> Stringers answers one question every day: what small product can one or two people build in a few months and actually make money from. Numbers come from 15 databases we collect daily, each with source and date.
> For agents: these verdicts and the underlying databases (verified revenue, App Store / Google Play charts, ad libraries, GitHub, Product Hunt…) are queryable live over MCP — tools today / hot / products / directions / direction / data. Setup: https://github.com/komako-workshop/stringers (the user logs in at stringers.io → "配置 agent" to get a personal URL). Site index: https://stringers.io/llms.txt

> LLMs bring the cost of example sentences, explanations and listening material for niche languages close to zero. Long-tail languages that weren't worth building before are now worth building.

[Home](https://stringers.io/worth/) / [021]

# Niche language-learning apps Duolingo doesn't do (sign language, Irish, Korean TOPIK exam...): one person builds one language, with native speaker review, subscription. Each single market is small, so spread across 2–3 languages.

Live Trackable · long-tail content app First spotted 2026-11-01 · Last updated 2026-11-02

Status

Live (small but steady; the high-revenue peers in the revenue library rely on paid acquisition and shouldn't be used as benchmarks)

Why now, and how long the window lasts

LLMs make example sentences, explanations, and listening material for niche languages nearly free to produce, so long-tail languages that were too costly to build before are now viable. Languages with strong identity (Irish, sign language) get users spreading them organically. The big platforms won't cover these long tails quickly, so the window isn't urgent (inferred).

Confidence

Medium (several apps are each holding steady in different languages); revenue-scale confidence is low (these organically growing apps have no revenue data). What would overturn this: HeyRua, Ziggy, and TOPIK Note all drop out of the top 100 of their main-store Education Top Grossing lists within 30 days; or Duolingo or Babbel launches in-depth courses in the same languages.

## Evidence

Grouped by store. Each group starts with the charts that can be graphed (real curves, data dates below the chart), then the scanner's original notes and source links.

### App Store3 evidence items · 6 products with curves

[Ziggy: Learn ASL Sign Language](https://apps.apple.com/us/app/ziggy-learn-asl-sign-language/id6781227577) OneDegree Labs LLC

App Store · launched 2026-07-21 · US store rating 7,147 · charted in 11-08 of 27 stores

Top Grossing chart rank · by store

Sri Lanka HN

Data 2026-11-03 → 2026-11-06 (4 days, 2 observations). Lower rank is higher; gaps mean it wasn't charted that day

Best category chart rank · US store

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Best rank across each day's category charts

[HeyRua - Irish Learning App](https://apps.apple.com/us/app/heyrua-irish-learning-app/id6796777994) BEIM DIGITAL LIMITED

App Store · launched 2026-08-16 · US-store rating 894 · best overall Top Free chart position #94 (Ireland) · 11-08 · charted in 6 stores 11-08

Top Free chart rank · by store

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Lower rank is higher; gaps mean it wasn't charted that day

Best category chart rank · US store

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Best rank across each day's category charts

[TOPIK Note](https://apps.apple.com/in/app/topik-note/id6761920888) Jihoon LEE

App Store · launched 2026-04-22 · Japan rating 498 · charted in 3 stores 11-08

Best category chart rank · by store

Japan Taiwan Hong Kong

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Lower rank is higher; gaps mean it wasn't charted that day

Rating count · Japan

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Apple doesn't publish download counts; rating growth is a proxy for downloads.

[HSK Note: Chinese Vocabulary](https://apps.apple.com/vn/app/hsk-note-chinese-vocabulary/id6809736935) Jihoon LEE

App Store · launched 2026-09-21 · South Korea rating 5 · charted in 1 stores 11-08

Best category chart rank · by store

South Korea Vietnam

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Lower rank is higher; gaps mean it wasn't charted that day

Rating count · South Korea

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Apple doesn't publish download counts; rating growth is a proxy for downloads.

[Daily Deutsch](https://apps.apple.com/us/app/daily-deutsch/id6757547901) Chandra Yadav

App Store · launched 2026-01-19 · US store rating 0 · charted in 11-06 of 1 stores

Ratings count · US store

Number of ratings 0

Data day 2026-11-06, only 1 days so far. Apple doesn't give download counts, so rating growth is the proxy

[Daily Deutsch: Learn German](https://apps.apple.com/au/app/daily-deutsch-learn-german/id6805159087) Joywise Labs Limited

App Store · launched 2026-09-08 · German rating 161 · 11-08 · charted in 41 stores

Best category chart rank · by store

Germany Italy Australia

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Lower rank is higher; gaps mean it wasn't charted that day

Rating count · Germany

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Apple doesn't publish download counts; rating growth is a proxy for downloads.

- App Store (11-02, Education Top Grossing): Ziggy: Learn ASL Sign Language (6781227577, OneDegree Labs, launched 2026-07-21) charted in 45 stores: lv #15, is #18, us #57, with 8,710 ratings across all stores; HeyRua Irish (6796777994, Beim Digital, 1 apps, launched 8-16): ie #3, ie overall Top Grossing #72, au #32, gb #39, us #95,1,832 with ratings.

- App Store (11-02, Education Top Grossing): TOPIK Note (6761920888, Jihoon LEE, Korean exam prep) charted #18 in the TW store (11-01 #10), #42 in JP, and #44,831 in HK, with ratings in each. The same developer also shipped a Chinese exam version, HSK Note (6809736935), which hit #116 on Education Top Grossing in the KR store. Daily Deutsch (6805159087, Joywise Labs) charted in 36 stores, best at #17 in the SI store, with 407 ratings across all stores (the report says 533).

- App Store (control group, report 11-01): Kori has only 29 ratings, VietBuddy 1, Verbi 118. Kori's self-reported acquisition channels are Instagram and Meta Ads. My guess is paid acquisition + a hard paywall + an annual plan. The listing only shows 0.7x annualized revenue.

### Google Play1 evidence items · 2 products with curves

[Ziggy: Learn ASL Sign Language](https://play.google.com/store/apps/details?id=com.ziggyasl.app) Ziggy ASL

Google Play · Launched 2026-09-03 · 11-07 installs 98,451

Global cumulative installs

Data 2026-10-29 → 2026-11-07 (10 days, 10 observations). Google's detail page only refreshes install counts every other day, so a flat day doesn't mean nobody installed.

Ratings (total)

Data 2026-10-29 → 2026-11-07 (10 days, 10 observations)

[HeyRua](https://play.google.com/store/apps/details?id=com.beimlimited.heyrua) Eamon Corcoran

Google Play · Launched 2026-08-16 · 11-07 installs 30,515

Global cumulative installs

Data 2026-10-29 → 2026-11-07 (10 days, 10 observations). Google's detail page only refreshes install counts every other day, so a flat day doesn't mean nobody installed.

Ratings (total)

Data 2026-10-29 → 2026-11-07 (10 days, 9 observations)

- Google Play (11-02): Ziggy com.ziggyasl.app has 89,977 installs and 6,884 ratings (about the same as iOS), #95 Education top grossing in us. HeyRua com.beimlimited.heyrua has 28,240 installs, #32 Education top grossing in gb (11-01 #27) and #74 in us. The report says TOPIK Note and Daily Deutsch are not on Play.

### Standalone product revenue (TrustMRR) 1 pieces of evidence

- Indie (revenue verified by payment platforms, as of 11-01, control group): Kori (learnkori.com, Korean) October $29,684; 30 days $28,270; 1,228 subscriptions; listed at $230,000. VietBuddy (Vietnamese) 30 days $24,922, 526 subscriptions, peaked for a week in October then fell back. Verbi (multi-language) September $128,508 → October $32,581. An anonymous Japanese app 30 days $13,393 (−27.5%), listed at $100,000.

## Already doing it

Ziggy (ASL), HeyRua (Irish), TOPIK Note and HSK Note (exam prep), Daily Deutsch, Kori, VietBuddy, Verbi, the anonymous Japanese app. Lock screen or widget "one word every hour" (Hourly Kana, Widget Vocabulary) is a separate opportunity, see [022].

## The hardest step

The ceiling and acquisition. Each language market is small (HeyRua is #72 overall in Ireland, already near the ceiling for that language). Growth without paid acquisition is slow, and with paid acquisition, profit is invisible, like Kori. Sign language needs video assets shot by hand.

## Who it's for

Indie devs with access to native-speaker reviewers. Choose languages with identity value (Welsh, Catalan, Cantonese, Taiwanese, Māori…). Subscription, with ASO and community doing the acquisition. Run 2–3 languages in parallel. The conversation-practice branch is in [023], and the playbook is in [019].

## Should every product builder know this?

No.

## Change log

2026-11-02

Backfill check: HeyRua #3 Education top grossing in Ireland and #72 overall top grossing (the report didn't mention Ireland). TOPIK Note tw #10→#18. Ziggy entered #95 Education top grossing in us on Play (the report says "not charted"). Kori's October final was $29,684; Verbi 30 days −74%.

2026-11-01

First logged (backfill sources: App Store new opportunities §1.5, Google Play new opportunities §4.1, revenue library §1.5, Stringers §3.2, data as of 2026-11-01).

Original: Scanner opportunity library #021 (updated daily, 06:00); this page was generated on the 2026-11-08 edition.