A privacy-first pattern tracker that connects the dots between your daily events, behaviors, and health outcomes — so you can take control of your wellbeing with real data, not guesswork.
No account required. Your data never leaves your device.
Maybe your headaches seem random. Maybe your energy crashes without warning. Maybe you suspect a food is causing issues but can't prove it. Doctors ask "have you noticed any patterns?" and you draw a blank.
The problem isn't that patterns don't exist — it's that the human brain isn't built to spot correlations across days, weeks, and months of messy daily life.
Undercurrent does this for you.
My daughter started getting headaches — not constantly, but often enough that we were worried. The pediatrician asked the usual questions: Is it stress? Screen time? Sleep? Diet? We didn't know. The headaches seemed random.
So I started writing things down. What she ate. How she slept. The weather. Her activities. After a few weeks of scattered notes, I realized I needed something better — something that could actually help me see patterns across all these variables.
That's why I built Undercurrent. Not as a medical tool, but as a way to finally answer the question every parent dreads: "What's causing this?"
Most health apps track one thing. Undercurrent tracks the connections between everything.
Symptoms, food, medications, activities, observations — capture events with a severity rating and optional notes. Templates and smart suggestions keep it fast.
Undercurrent analyzes your data for pre/post event correlations, recurring sequences, clusters, streaks, and time-of-day patterns — all using deterministic, explainable algorithms. No black boxes.
Automatically captures weather, barometric pressure, humidity, air quality, and UV index for each event. See how environmental factors correlate with your symptoms over time.
Automatically imports workouts and mindful sessions from Apple Health — including 25+ workout types like running, cycling, swimming, yoga, and strength training. Connects your activity data to your logged events to find patterns you'd never spot manually.
Undercurrent learns your patterns and predicts when you're most at risk based on day of week, time of day, recent triggers, and current environmental conditions. Know what's coming before it hits.
Generate detailed PDF reports with symptom analytics, risk factors, protective factors, environmental correlations, and a full event timeline. Turn "I think maybe..." into "the data shows..."
Optional AI-powered natural language explanations of your patterns with research-backed citations, running entirely on your device. Your data never touches a server.
Encrypted iCloud backups protect your data with AES-256 encryption and a password only you know. Your data stays private even in the cloud.
Decades of research show that self-monitoring is one of the most effective tools for understanding and improving your health.
A systematic meta-review found that self-monitoring is one of the most consistently effective behavior change techniques across health domains. A separate umbrella review of 85 studies with 865,000+ participants confirmed self-monitoring, feedback, and goal-setting as the most effective components of digital health interventions.
Samdal et al., 2020 — Health Psych ReviewPark et al. found that symptom diary use was associated with improved survival in heart failure patients. A randomized controlled trial showed that an eHealth diary improved patients' self-efficacy, leading to better disease management and fewer hospital visits.
Hagglund et al., 2016 — JMIRA PLOS One study analyzing 4,579 days of smartphone diary data from 62 participants confirmed the app was an effective tool for assessing migraine trigger factors. A 2025 study showed that the unexpectedness of daily experiences predicts migraine risk within 24 hours.
Park et al., 2016 — PLOS OneResearch found that visual data summaries enabled both patients and providers to focus on individualized, actionable plans rather than vague recollections. Tracking bridges the gap between your lived experience and your doctor's medical expertise.
Chung et al., 2019 — PMCA comprehensive review established that meteoropathy is a recognized condition, not a myth. Barometric pressure, humidity, and temperature changes affect neurotransmitter levels and are linked to migraines, joint pain, and mood changes. 30–50% of migraine patients report weather as a trigger.
Bertazzi et al., 2023 — PMCDigital diaries have higher adherence rates than paper, with automatic reminders and backup. A meta-analysis found that digital self-monitoring significantly improved weight loss, physical activity, and calorie reduction compared to non-tracking controls.
Berry et al., 2021 — Obesity ReviewsHealth apps routinely share data with advertisers without consent. One study found that health apps transmitted user data to an average of 7 third-party services. Another found that algorithms can re-identify 85.6% of adults from supposedly anonymized health data.
Undercurrent takes a fundamentally different approach.
All your data lives on your device in a local database. There is no cloud sync by default, no server that stores your health information.
Start tracking immediately. No email, no sign-up, no profile. Nothing to breach because nothing is collected.
iCloud backups are encrypted with AES-256 and a password only you know. Even Apple can't read your data.
AI features run entirely on your phone using a local model. Your data is never sent to OpenAI, Google, or any external service.
Privacy concerns sourced from: Health Policy and Privacy Challenges (PMC, 2020) · Brown University Center for Digital Health, 2023 · npj Digital Medicine, 2021
Migraines, IBS, fibromyalgia, autoimmune conditions, chronic fatigue — track symptoms alongside potential triggers to find what actually helps.
Suspect a food is causing issues? Log meals and symptoms and let the pattern analysis reveal delayed reactions you'd never catch manually.
Monitor whether a new medication or supplement is actually working by tracking outcomes before and after starting it.
Understand how sleep, exercise, weather, and habits affect your energy, mood, and focus. Stop guessing, start knowing.
No account. No data collection. No strings.