Small apps that do one thing
These are not a suite. Each of the 10 apps here started because something was annoying enough to fix: a subway app that needed a signal underground, a notes app that filled up with notes nobody ever read again, a vocabulary drill that only existed as a paper book. They are built one at a time, by a very small team, and they stay deliberately narrow.
That narrowness is the point. An app that does one thing can open instantly, work offline, and be understood in a minute without a tutorial. None of them ask you to create an account before you can see what they do.
No ads on these pages
The tool pages on this site carry a small number of ad slots, which is what pays for the site. The app pages do not. No banners, no interstitials, no tracking pixels following you to the store. You came here to decide whether an app is worth installing, and an advert sitting in the middle of that decision helps nobody.
What you will find
- Study and language — TOPIK practice tests with instant scoring, a general practice-test app with timed and review modes, English games for young children, and a reader that scans a printed English page, reads it aloud and translates any word you tap.
- Money and habits — a spending tracker built backwards: instead of logging what you bought, you log what you did not buy, and watch the total you resisted grow.
- Notes — a notepad whose notes delete themselves, for the thought you need for ten minutes and never again.
- Travel — the Seoul, Incheon and Gyeonggi metro in one offline app, with live arrivals, real timetables and routing that keeps working underground.
- Hardware — Bluetooth Low Energy tools for STEM kits and a serial monitor, for people building things with Arduino and ESP32 boards.
Languages and regions
Several apps exist as more than one store listing rather than one app with a language menu, because a Korean lottery checker and a Vietnamese study app are not the same product with different words — they have different data, different rules and different users. Where that is the case you will see both listings above, each marked with its flag. Other apps simply follow your phone's language.
Common questions
Are the apps free?
Every app listed here is free to download. Where an app has a paid option, it is described on that app's own page before you reach the store.
Android or iOS?
It varies by app, and each card above shows which stores that listing is on. Most are on Google Play; some are on both.
What data do the apps collect?
Each app has its own privacy policy, linked from its page and from the store listing. Several of them store everything on your device and send nothing anywhere.
An app is missing a language I need.
Tell us which one — see the Contact page. Localisation is usually the cheapest change to make, and requests genuinely drive the order it happens in.
Where are the web tools?
On the Tools page — a separate library of browser-based tools and converters that need no install at all.