About Me
Developer · Builder · Based in Singapore
Hi, I'm Duc Nguyen — a software developer who builds practical tools and writes detailed technical guides. Everything I publish here is created to be genuinely useful: the tools run entirely in your browser (so your data never leaves your device), the guides are written from real experience, and the digital products are things I use myself.
What I Build
I focus on a few principles that shape every project:
- Privacy by default. My online tools are 100% client-side. No data is sent to a server, no tracking of what you type, no sign-up required. What you compute stays on your machine.
- Zero dependencies where possible. My open-source libraries use only the Python standard library or browser-native APIs. This keeps them fast, secure, and easy to audit.
- Depth over volume. I'd rather write one thorough guide that solves a problem completely than ten shallow ones. The article archive reflects real debugging and research, not generated filler.
The Projects
This site is a hub that connects several focused projects, each maintained independently:
- Free Tools Hub — a growing collection of browser-based utilities: JSON formatter, Base64, password generator, QR maker, and more.
- Crypto Brief — clear, jargon-free explainers of cryptocurrency and blockchain concepts.
- Finance Daily — practical personal finance and money-management guides.
- Health Today — evidence-based health and wellness information.
- Productivity Hacks — workflows and systems for getting focused work done.
- AI Tool Hub — curated AI tools and how-to guides for using them well.
- Duc Store — my digital products (ebooks, templates, developer assets).
"Build the tool you wish existed — then make it free, private, and fast."
Open Source
Most of my code is open source on GitHub, including libraries for AI agent memory, JSON repair, configuration loading, and LLM cost estimation. I believe useful code should be readable, tested, and shared.
How This Site Is Supported
This site is supported through a mix of digital product sales (via Gumroad, Payhip, and Stripe), optional sponsorships, and contextual advertising. Advertising never affects which tools I build or what the guides recommend. Tools remain free and private regardless.
Get In Touch
If you have a question, found a bug, or want to suggest a tool, the fastest way to reach me is through the contact page or directly on GitHub. I read everything, even if I can't reply to all of it.