Sabujak Works
Sabujak Works is a one-person studio that makes web services, iPhone and Android apps, and games. It is the brand of HS24 (에이치에스이십사), a sole proprietorship registered in the Republic of Korea. Hyeonsu Jeong owns the business and plans, builds and runs every product alone. The rest of this site is in Korean.
Company details
- Legal name
- HS24 (에이치에스이십사)
- Business type
- Sole proprietorship, Republic of Korea
- Representative
- Hyeonsu Jeong (정현수)
- Business registration no.
- 380-17-02125
- Brand
- Sabujak Works (사부작 웍스)
- hello@sabujakworks.com
- Hosting
- Google LLC (Firebase Hosting)
Released products
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Cushion Keepers: Cat Defense (방석 사수!)
ReleasedA lane defense game. You place cats on a grid to stop household items and toys from reaching a nap cushion. A round lasts about 30 seconds.
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출생국가 랜덤가챠 (Born Somewhere)
ReleasedDraws a country weighted by population or annual births, then plays out a short fictional life in four choices. Country figures come from UN, World Bank and UNDP statistics.
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Maeum Birthday Book (마음 한 권)
On the webA Korean web service for making a pop-up birthday book with a letter and a photo, then sending it as a link. You can make one without signing up.
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러브레터.zip (Loveletter.zip)
ReleasedYou design a date invitation and send it as a link. The person who gets it accepts and picks the date, time and menu.
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Orbit Lab (궤도실)
On the webA 3D astronomy simulation of the solar system and the ecliptic from 1900 to 2050. You can look up planet positions, the 24 solar terms and eclipses by date.
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말랑대전 (Mallang Battle)
ReleasedEight animals compete in a knockout tournament, and you predict the winner of each match before it starts. No login needed.
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Fractal Travel
ReleasedIt draws 25 kinds of fractals in real time on the device. You pinch to zoom, or turn on auto zoom to keep going deeper. The Apple TV version is a separate app called Fractal Travel Wide.
In preparation
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Mochi Meow (말랑냥)
Not released yetA kitten-raising game. You pet, feed, bathe and put a kitten to bed until it grows into an adult cat.
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Snugbox Cats: Block Puzzle (상자 쏙!)
Not released yetA block puzzle where you drag soft cat blocks into a box and clear full rows or columns. It has no ads and works offline.
Names shown on the app stores
On the App Store, the seller name is "hyeonsu jeong", the owner's personal developer account. On Google Play, the developer name is "HS JEONG". Both accounts belong to Hyeonsu Jeong, and every store app on this page was published through them.
How the work gets done
Hyeonsu Jeong handles planning, development, store submissions and day-to-day operation. Much of the development is done with Claude Code, Anthropic's coding agent. The web front ends are served from Firebase Hosting.
Contact
Write to hello@sabujakworks.com for partnerships, general questions, app support or privacy requests. You can write in English or Korean, and the reply will be in the same language.