I build small software products — and write down how they actually run.
I'm Junhua. I ship small Mac apps and write field notes on building and running them.
I also take on a few freelance projects. See selected work →
Builder & writer
Field notes
Building & operating
Indie economics, real operating costs, and the decisions behind running small products.
- 给 MarginDeck 接入 MCP
- TakaQuiz: Rising Installs, Falling Weekly Active Users, and Five First-Session Failures
- I Reviewed Seven Products in One Afternoon and Killed Four
- Google Search Console & Bing Webmaster Tools: Setup and "No Data" Fixes
Reverse engineering & security
CTF write-ups, ARM assembly, and notes on memory, exploitation, and tooling.
- PWN - Sice Cream
- Heap Exploitation - how2heap - house_of_orange
- Heap Exploitation - how2heap house_of_roman
- Heap Exploitation - how2heap 3
Product finance guides and tools
Shared cost allocator
Split one monthly shared-cost pool across products in a single scenario. Nothing is uploaded or saved.
Open allocator ↗Runway calculator
Estimate how long current cash lasts against monthly burn, and see when the balance reaches zero.
Open calculator ↗MarginDeck
A local-first Mac app for revenue, costs, and estimated contribution profit — with a menu bar brief for quick checks.
Compare revenue, scheduled costs, and estimated contribution profit across products over 6 or 12 months — and check the next 7 or 14 days of scheduled costs without opening a dashboard.
- Platform
- Native macOS
- Data
- Local-first
- Starting point
- One product free