Live product
kardfolio
A cross-platform product that turns recurring credit-card complexity into a calm decision workflow.
- Proof
- Product judgment, domain modeling, web + native iOS
- Role
- Solo founder and product engineer
Calvin Hsieh
Product Engineer / AI Product Engineer
Product judgment → shipped system
I turn ambiguous product problems into shipped software.
I work across product decisions, interfaces, systems, and release—and use AI inside explicit evidence and approval boundaries.
Inspect kardfolio
Selected work
Two ways I build.
Operating system
CalvinOS
An AI operating layer that keeps source truth, human judgment, external authority, and verification inspectable.
- Proof
- One real Product Content Ops run and failure replay
- Role
- Designer and builder
Working method
Evidence before claims. Judgment before velocity.
- Frame
Define the user decision and the constraints that matter.
- Model
Make difficult concepts explicit across product and systems.
- Build
Move hands-on across interface, backend, native, and release.
- Verify
Keep agent work bounded, reviewable, and human-owned.