Wearables

A practical, tiered guide to the quantified self stack for developers — from HRV and sleep tracking through CGM and blood biomarkers — focused on the metrics that move the needle on cognitive output, not just vanity numbers.

Heart rate variability is the most actionable biometric a developer can track. Here's what HRV actually measures, which devices work, how to interpret your trends, and how to use the data to make smarter decisions about training, sprint work, and recovery.