Flexible Activity and Symptom Tracker (FAST) is developed for patients with chronic illness and their healthcare professionals. FAST Diary can be used to record effects of treatment on subjective experiences such as pain, mood or fatigue. Simple numerical or word rating scales are set up as appropriate for the symptom that is being treated. Relevant activity, for example, medication use or physical exercises, can be indicated using the app too. Feedback from the patients is charted on a simple graph and communicated to the healthcare professional. FAST was developed by FatFractal, Inc. for the Evelyn Trust, Cambridge University Hospitals NHS Trust and the University of Cambridge.