Mobile App Development for Productivity & Health
Portfolio of independent developer Yang Sun, featuring Handwriting Book, PrivAI, Life Cabinet and more.
Featured Applications
Each app is carefully designed to improve your quality of life
QuickNotes Flashcards Watch
Effortless Exam Prep and Study
A flashcard note app designed for exam review and knowledge accumulation, supporting seamless sync between iPhone and Apple Watch.
PrivAI LLM - Local AI Chat
Local Offline LLM AI Chat
An intelligent application based on DeepSeek-R1 distilled models, designed for users who value privacy, convenience, and versatility.
Life Cabinet
Manage Your Life Blueprint by Departments
A comprehensive life planning and growth management tool that coordinates health, finance, career, learning and other aspects through departmental management.
Copybook
Handwriting Focus & Calm
A digital space for mindfulness through handwriting, helping you regain focus and calm.
R90 Sleep Assistant
Manage Your Sleep Cycle
Based on the R90 sleep method, helping you plan sleep by cycles, eliminate sleep anxiety, and regain energy.
Self-Love Project
Stop Self-Hate, Start Self-Love
Stop hating yourself into improvement. Use 'Identity Switching' rituals and a 21-day challenge to become your better self with love.
GeoFlow
Geo Arbitrage & Budget
Turn the world into your wallet. Multi-currency budgeting and geo-arbitrage analysis tool designed for digital nomads.
Rich Dad Finance Tracker
Build Assets, Not Just Budgets
A financial tool based on 'Rich Dad Poor Dad' principles, helping you distinguish assets from liabilities and focus on cashflow and passive income.
PetSitter Pro: Client Manager
Schedule, Invoice & Reports
Designed for independent pet sitters and dog walkers, helping you turn from 'amateur part-time' to 'industry expert'.
SkillHub: Discover AI Skills
Find & Save Pro Agent Skills
Build AI-driven businesses with 150+ ready-to-use skills. No coding, three-step setup.
Blog
Sharing iOS development experience, ASO tips, and product design insights.
10 Best Games Like Unpacking on iOS (2026 Cozy Puzzle Picks)
Played Unpacking but can't find a mobile version? This list covers the 10 best iOS games that capture the cozy organization magic of Unpacking — from box unpacking to room decorating.
Read moreBack to School Survival Guide: 10 Apps to Switch from Summer Zombie to Semester MVP
Two weeks left of summer. Sleep schedule wrecked, paper untouched, presentation unprepared. This guide uses 10 apps across study, communication, life management, and sleep to build your back-to-school operating system.
Read moreInfinite Craft Rare Recipes Top 20: 99% of Players Have Never Crafted These
Think Infinite Craft stops at 'Human' and 'Elon Musk'? This rare recipe list will blow your mind. Even better: the multilanguage version has exclusive cross-language Easter eggs — type the same concept in Chinese and English, get completely different results.
Read more7 Common MET Tracking Mistakes: You Might Be Working Hard Wrong
Think you're tracking MET correctly? From daily target anxiety to ignoring intensity, here are 7 common mistakes and how to fix them. The science behind MET is about weekly accumulation, not daily closure.
Read moreAbout Indie Developer Yang Sun
As an independent developer focused on mobile apps, I believe technology should serve life, making complex things simple and beautiful experiences accessible.
Since starting iOS development in 2020, I have released 55 apps covering productivity, health, learning, and more. Each app embodies my pursuit of user experience and product quality.
User Experience
Every detail carefully polished
Innovation
Following trends, exploring possibilities
Service
Listening to feedback, improving constantly