I build small, careful software
Native apps, browser extensions, and web tools — usually with a privacy bent. I like things that are quiet, fast, and honest about what they do with your data.
About
Pengfan Chang
Hacker, researcher, and outdoor wanderer. I build software, poke at data, and write down what I learn on both sides of the tree line.
The short version
Hi — I'm John. I've been taking computers apart and putting them back together since I was a kid, and I never really stopped. These days I run Swipht Group, where I make small, privacy-minded apps and tools.
The other half of me lives outdoors. Long hikes, cold mornings, and the kind of quiet you only find a day's walk from the trailhead. That patience leaks into how I build: I like tools that are light to carry, clear under pressure, and honest about their limits. This blog is where the two halves meet.
What I spend my time on
I dig into data
SQL, Python, and a lot of spreadsheets. I enjoy the moment where a messy pile of numbers finally tells you something true.
I work in the open
Most of what I make is public and readable. Source, notes, and mistakes included — it keeps me honest and occasionally helps someone else.
Snapshot
- Name
- Pengfan Chang (people call me John)
- Day job
- Founder of Swipht Group
- Home base
- Wherever the work and the mountains overlap
- Languages I reach for
- Pascal, C, Go, Java, Kotlin, Swift, Python, SQL
- Platforms
- GNU/Linux, macOS, iOS, iPadOS, watchOS, visionOS, Android, the open web
- Research identity
- ORCID 0009-0002-9408-5801
- Also here
- GitHub, LinkedIn, ORCID, Bluesky, YouTube
Toolkit
Native
- Swift
- SwiftUI
- Kotlin
- Java
- Flutter
- Dart
- StoreKit
Web
- Astro
- TypeScript
- Preact
- Cloudflare Pages
- Workers
- D1
Data
- SQL
- Python
- Excel modeling
- Plotly
- research notebooks
Keeping it honest
- Vitest
- Playwright
- accessibility checks
- CSP
- rate limits
Away from the keyboard
When I'm not shipping code you'll usually find me somewhere with worse cell signal and better views — hiking, backpacking, taking photos, and learning to read the land. There's a particular clarity that shows up around the second night out that I haven't found anywhere else.
A fair number of posts here start on a trail and get written up once I'm back and thawed.
Say hello
My code lives on GitHub and my company lives at Swipht Group. For anything else, the contact page is the fastest way to reach me.