Ecological Momentary Assessment · Experience Sampling
ExpiWell: the leading platform for ESM & EMA research
High-fidelity, real-world data collection and analytics for scientific discovery — created by researchers, for researchers. Launch a study in minutes, capture life as it happens, and turn moments into insight. Born out of Purdue University; HIPAA-aligned and GDPR-compliant.
What are EMA and ESM?
Ecological Momentary Assessment (EMA) and the Experience Sampling Method (ESM) are research approaches that repeatedly capture people’s thoughts, feelings, behaviors, and contexts in real time, in their natural environments. By sampling experience in the moment, they reduce recall bias and reveal how well-being and behavior unfold across days, situations, and people.
ExpiWell is a modern, no-code software platform that makes ESM and EMA research easy to design, deploy, and analyze — on iOS, Android, and the web. It was founded by Dr. Louis Tay, director of the WAM Lab at Purdue University, together with technologist Justin Rahimi, to give researchers the capabilities that off-the-shelf survey tools could not provide. Born out of Purdue University and backed by Elevate Ventures, it is HIPAA-aligned, GDPR-compliant, and trusted by IRBs in medical and clinical settings.
Capabilities
Everything you need for real-world research
Adaptive mobile surveys
Design sophisticated EMA/ESM surveys with branching logic, diverse question types, and flexible, repeated scheduling.
Smart scheduling & reminders
Signal-, interval-, and event-contingent prompts with push notifications and reminders that automatically adapt to each participant’s time zone.
Wearables & passive sensing
Combine self-reports with passive data from Apple Watch/HealthKit, Fitbit (daily and intraday), BACtrack Skyn, and smartphone sensors for a fuller picture of daily life.
Geofenced & context triggers
Run geographically explicit EMA (gEMA): surveys fire the moment participants arrive at or leave a place — for clinic, campus, and community studies.
Real-time analytics dashboard
Monitor response rates and compliance live, visualize incoming data, and link responses anonymously over time.
Participant management & payments
Recruit, track, and pay participants anonymously through free native iOS and Android apps available in 13 languages.
Security & compliance
HIPAA-aligned with signed BAAs, GDPR-compliant with EU data residency, AES-256 encryption, and WCAG 2.1 AA accessibility — continuously monitored, with SOC 2 in progress.
IRB & grant support
Data-privacy documentation researchers can cite in an IRB application, guidance for grant proposals, and a peer-reviewed publication record across psychology, medicine, and organizational science.
Free to start, flexible to scale
A Free Basic plan with unlimited participants, responses, and projects — then add scheduling, adaptive triggers, sensors, or gEMA as your method needs them, with graduate-student and department pricing.
Voice, video & automatic transcription
Participants answer in their own words with audio, video, image, and text capture — then recordings are auto-transcribed for analysis, alongside cognitive testing modules and just-in-time adaptive interventions (JITAIs).
So I did a thing …
In 2013, I realized there was no platform that could conveniently conduct ecological momentary assessment (EMA) and experience sampling method (ESM) research. Survey tools existed, but none could do all of the following at once: schedule surveys, send notifications and reminders, adapt to participant time zones, link surveys anonymously over time, dashboard ongoing response rates, pay participants, visualize incoming data, and connect to wearables.
So I created ExpiWell to do all of that — and more. Today it proudly serves more than 7,000 researchers in over 20 countries and keeps growing to advance ESM and EMA research.
Leadership
Meet the co-founders
ExpiWell pairs academic leadership in the science of daily experience with two decades of engineering leadership — so the platform stays rigorous as a research instrument and dependable as software.
Justin Rahimi
CEO & Technical Co-Founder
As CEO, Justin defines ExpiWell’s strategic vision while driving the operational excellence and team building that turn that vision into reality. As Technical Co-Founder, he leads the company’s systems architecture, designing the secure, scalable foundation that complex research methodologies demand.
He brings over two decades of leadership, management, and technical expertise, having guided engineering organizations across healthcare, global manufacturing, government, and fintech.
Louis Tay, Ph.D.
Co-Founder · William C. Byham Chair Professor
Dr. Louis Tay is the William C. Byham Chair Professor of Industrial-Organizational Psychology at Purdue University and director of the WAM Lab, where ExpiWell began. His research joins well-being, character strengths, and vocational interests with measurement and data science.
He is co-editor of Big Data in Psychological Research and the Handbook of Well-Being, his work has been featured in the Wall Street Journal, Washington Post, TIME, and Scientific American, and he advises Fortune 500 organizations on well-being and on bias in machine learning.
They are supported by an in-house engineering team, a customer success team, and a scientific advisory board of researchers who keep the platform grounded in peer-reviewed science.
FAQ
Frequently asked questions
What is ExpiWell?
ExpiWell is a research platform for Experience Sampling Method (ESM) and Ecological Momentary Assessment (EMA) studies. It lets researchers design adaptive mobile surveys, schedule real-time prompts, integrate wearables and sensors, pay participants, and analyze data on a unified dashboard — across iOS, Android, and the web.
What is the difference between EMA and ESM?
The terms are closely related and often used interchangeably. The Experience Sampling Method (ESM) repeatedly samples people’s momentary experiences (thoughts, feelings, activities) in daily life, while Ecological Momentary Assessment (EMA) emphasizes real-time assessment of behaviors and states in natural (ecological) settings. Both reduce retrospective recall bias and capture within-person change over time.
Who created ExpiWell?
ExpiWell was co-founded by Dr. Louis Tay, William C. Byham Chair Professor of Industrial-Organizational Psychology at Purdue University and director of the Well-Being, AI, and Measurement (WAM) Lab, and Justin Rahimi, who serves as CEO and technical co-founder. The company was born out of Purdue University, and its lead investor is Elevate Ventures.
Who uses ExpiWell?
It is used by 7,000+ researchers across 1,000+ institutions in more than 20 countries, including academic psychologists, clinical and healthcare researchers, educators, organizational scientists, pharmaceutical teams, and market researchers.
Does ExpiWell support wearables and sensors?
Yes. ExpiWell can collect passive data from wearables and devices such as Apple Watch/HealthKit, Fitbit (daily and intraday), and BACtrack Skyn, as well as smartphone sensors and GPS, to complement self-reported survey responses.
Can I schedule notifications and pay participants?
Yes. ExpiWell supports signal-, interval-, and event-contingent scheduling with time-zone-aware push notifications and reminders, live compliance monitoring, and built-in participant payments.
Is ExpiWell HIPAA and GDPR compliant?
Yes. ExpiWell is HIPAA-aligned — built for Protected Health Information with signed Business Associate Agreements, AES-256 encryption at rest, TLS in transit, and audit trails — and GDPR-compliant with EU data residency and appointed EU and UK representatives. Controls are monitored continuously, the platform follows WCAG 2.1 AA accessibility guidelines, and SOC 2 certification is in progress.
Do I need to know how to code?
No. ExpiWell is a no-code platform: studies are built in a visual designer, and many researchers design and launch a full ESM study in a single afternoon. A Free Basic plan with unlimited participants, responses, and projects lets you start without a subscription.