About

I'm Joyce Jin, born in 1992, based in Shanghai.

Ten years in growth and monetization: product ads at Baidu's ad platform, the growth platform and monetization at Qutoutiao, group growth at CooTek, and the user growth center at China Literature. Now I define AI-native hardware products, owning model capability evaluation and the data pipeline.

This site covers four things:

• AI hardware: devices I paid for, wore, and took apart. Whoop, Oura, the Samsung ring, Fitbit Air, always-on recorders. How they work, whether they're worth it.
• Wearable health data: five devices on my body at once. Do the numbers agree, and which ones can you trust.
• Multimodal memory benchmarks: I wore a recorder for weeks and used hundreds of hours of my own real audio to write exams for AI. What did it actually remember.
• Unit economics: every extra generation in an AI product costs real money. Do the math on day one.

One rule: every number comes from my own devices and experiments. If I'm not sure, I cut it.

I row competitively as an amateur, with strength and conditioning every week.

Contact details are in the footer.