About SK APPS

Independent developer building useful, well-designed mobile apps and web tools — for everyone, in every language.

Who we are

SK APPS is the publishing identity of Kenichiro Sakamoto, an independent software developer based in Japan. Since 2024, SK APPS has shipped 98+ mobile applications on the Google Play Store and the Apple App Store. In 2026 we expanded to the web with Toolify (tools.appdevelopsk.com) — a growing collection of free, browser-based calculators and utilities.

What we do

Our work spans three categories:

Mobile games and quizzes

Quick, engaging games and trivia that work in 30 seconds or 30 minutes. Examples: 30sec Challenge, Brain Burst, Key Clash, Geo Sense.

AI-powered tools

Practical AI applications for everyday use: photo-based vocabulary learning (SnapLingo), voice journaling (Voice Memo), conversational practice (Debate Me), AI life logging (Life Trace).

Reference encyclopedias

Beautifully illustrated reference apps covering the natural world: dinosaurs, marine life, mushrooms, birds, plants, gemstones, world flags, world heritage sites, and more.

Web tools (Toolify)

Free, instant calculators and converters that run entirely in your browser. BMI, calorie, due-date, retirement, ovulation, regex tester, hash generator, and 60+ more — covering health, finance, math, datetime, text, color, and unit conversion.

Our principles

• Useful by default. Every app and tool should solve a real problem. We do not chase trends.
• Privacy-first. Most web tools run entirely in your browser; nothing is transmitted unless explicitly required. Mobile apps clearly disclose data collection in their individual policies.
• Global from day one. All apps and tools support 17 languages: English, Japanese, Chinese (Simplified and Traditional), Korean, Spanish, Portuguese, French, German, Italian, Russian, Arabic, Hindi, Indonesian, Thai, Vietnamese, and Turkish.
• Built to last. Apps run native on iOS and Android. Web tools are static, fast, and independent of any external API.

Technology

Mobile apps are built with Flutter, allowing us to ship to both iOS and Android from a single codebase. Web tools (Toolify) use Next.js 15 with full static generation, deployed on a global CDN. We use TypeScript, PostgreSQL, and Redis on the server side where needed.

Get in touch

We are a small operation. We read every email and reply personally.