Undercurrent: Symptom Tracker

A private notebook for symptoms, food, sleep, and the patterns hiding inside them. On-device. No account. One-time purchase, no subscription.

You know something is off, but what?

Headaches that seem random. Energy that crashes for no reason. You suspect a pattern, but every time the doctor asks "have you noticed any patterns?" you draw a blank.

Undercurrent is a private notebook for the small things, and the patterns hiding inside them.

LOG IN FOUR TAPS OR FEWER Symptoms, food, medications, activities, and observations. Quick chips for what you log most. Or just tell the on-device AI assistant in plain language: "headache after lunch" and it handles the rest.

WHAT WE'VE NOTICED Once you've logged a few events, the Insights page surfaces co-occurrences in your own data, phrased in soft language. None of it claims to cause anything. You decide if it's signal or noise. • Pre-window pattern: what tends to show up in the hours before symptoms • Time-of-day cluster: when symptoms tend to gather • Day-of-week peak: which days run hottest • Recurring sequence: a familiar arc, repeated • Co-occurrence: tags that appear alongside symptoms • Seasonality: a year, at a glance (Pro) • Environment: weather, pressure, humidity, air quality (Pro) • Long-term cycles and intervention effectiveness (Pro)

A REPORT YOU CAN HAND TO YOUR CLINICIAN (Pro) One tap exports an editorial PDF: auto-numbered observations, frequency tables, time-of-day distributions, and an event log. Black-and-white printable, sized for a five-minute appointment. No portal login on the other end.

APPLE HEALTH INTEGRATION (Pro) Pull in workouts and mindful sessions automatically. The data stays on your device and is folded into the same patterns engine.

TRACK MULTIPLE PEOPLE (Pro) Separate threads for yourself, your kids, or anyone you care for. Each thread gets its own timeline, observations, and reports.

100% PRIVATE BY DEFAULT • No account required, start logging immediately • All data stored locally on your device • AI runs on-device using Apple Intelligence; nothing is sent to a server to be analysed • Optional iCloud backup, protected by Apple's encryption • No analytics, no tracking, no ads

BUILT ON PUBLISHED RESEARCH Self-monitoring is the most effective technique in digital health interventions for chronic conditions, backed by analysis of 85 clinical studies. Smartphone diaries have been shown to identify real triggers; visual diary summaries help patients and providers focus on actionable plans.

FREE FOREVER • Unlimited logging of symptoms, food, meds, actions, observations • Today, Timeline, and Calendar views • AI chat assistant for plain-language logging • Basic Insights: pre-window, time-of-day, day-of-week, sequences, co-occurrences • Local-only data, stays on your device

UNDERCURRENT PRO · ONE-TIME PURCHASE · $19.99 Pay once, keep everything forever. No subscription, no recurring charges. • Weather, pressure, and humidity correlations • Long-term cycles, seasonality, intervention effectiveness • Editorial PDF report for your clinician with full observation set • Track multiple people, with separate threads for each • Apple Health sync • iCloud backup

Whether you're trying to figure out what shows up before your migraines, why your energy crashes after lunch, which foods leave you uncomfortable, or what helps your child sleep better, Undercurrent gives you a quiet place to write it down and the patterns that emerge over time.

NOT A MEDICAL DEVICE Undercurrent describes statistical co-occurrences in your self-logged data. It is not intended to diagnose, treat, cure, or prevent any disease. Observations are informational only, not medical advice. Always consult a qualified healthcare professional about symptoms, medications, or treatment decisions. In an emergency, call your local emergency number.

Notice what's quietly shaping how you feel.