Undercurrent vs Truly Simple Symptom Log

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 symptom log and food diary for the small things, and the patterns hiding inside them. Use it as a headache log, a food symptom diary, or a flare journal for a chronic illness. LOG IN FOUR TAPS OR FEWER Symptoms, food, medications, activities, and observations. Quick chips for what you log most. Voice if you'd rather. 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 enough 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, barometric pressure, humidity, air quality, for migraine weather and pressure patterns (Pro) • Long-term cycles and intervention effectiveness (Pro) A REPORT YOU CAN HAND TO YOUR CLINICIAN 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. READINGS: GLUCOSE, HEART RATE, BLOOD PRESSURE, WEIGHT Your numbers sit on the same timeline as everything you log. Log a reading by hand in a couple of taps, or import from Apple Health with Pro, including a CGM's glucose every five minutes. ON YOUR WRIST Log what you log most with one tap on Apple Watch. Set severity with the Digital Crown, mark a symptom improved later, or start from its watch face complication. MEDICINE CABINET AND PILL BOX Set a dose schedule once and the medications you take regularly log themselves. A daily pill box shows what's taken and what's still due. APPLE HEALTH INTEGRATION Pull in workouts, mindful sessions, and readings automatically (Pro). TRACK MULTIPLE PEOPLE (PRO) Separate threads for yourself, your kids, or anyone you care for. 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 Across 85 clinical studies, self-monitoring was the most effective technique in digital health interventions for chronic conditions. FREE FOREVER • Unlimited logging, medicine cabinet, and manual readings • 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 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 • Full clinician PDF report • Multiple people • Apple Health sync, including CGM glucose • iCloud backup Whether it's what shows up before your migraines or which foods leave you uncomfortable, Undercurrent gives you a quiet place to write it down. 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.

Truly Simple Symptom Log is built around a single conviction: health tracking should take seconds, not minutes. Most symptom trackers are overbuilt and cluttered with complicated graphs, gamification, mandatory onboarding, and subscriptions that make the act of recording how you feel a chore. This app strips all of that away. It features a calm, minimal, one-screen logging interface that feels closer to a personal journal than a medical tool. It’s perfect for people with chronic conditions, people exploring cause-and-effect with their health, or anyone who just wants a friction-free way to log their mood and symptoms and then move on with their day. There's an in-app purchase that allows you to lock the app and export your data, but all core features are available in the free version and can be used for free as long as you like. Features: • One-screen logging: Record your mood, symptoms, potential causes, and notes on a single page. No tabs or multi-step wizards. • Heatmap calendar: A color-coded monthly data view gives you an instant visual summary of how you've been feeling over time, so patterns become obvious at a glance. • Accessible by design: Enlarged, comfortable touch targets prevent mis-taps when you're not feeling well. Fully optimized for VoiceOver screen readers and scalable dynamic text for low vision. • iCloud Sync: Logs sync silently and automatically across your Mac, iPhone, and iPad. Status indicators let you know your data is secure at a glance. • Free core features: All core logging is completely free. A single one-time, lifetime purchase unlocks optional data exports and a biometric privacy lock.