Endometriosis is a chronic incurable disease where endometrial-like tissue grows outside of the uterus, and causes symptoms such as debilitating menstrual pain, pain during intercourse, infertility, constipation, and bloating, which hurts their quality of life. Endometriosis is estimated to affect approximately 10% of women. Despite this, there's currently not enough research on this disease; in Canada it takes on average 5.4 years to get a diagnosis (from when symptoms start), and once diagnosed, women often have to go through a trial-and-error process to find a treatment that can manage their symptoms. Misunderstanding symptoms and struggling with patient-provider communication both contribute to these delays in diagnosis and finding the best treatment. Mobile health applications have been a promising new tool to self-track symptoms and treatments. There are several apps currently available on the market for logging chronic pain, menstrual cycles, and fertility. However, no apps exist specifically for endometriosis that look at the whole spectrum of symptoms, including pain, quality of life, and especially ease of patient-provider communication. The elleFA app is a new, personal endometriosis and health tracking app designed to improve patient-physician dialogue through more direct, efficient, and impactful communication, as patients navigate their condition. This single-arm interventional study aims to test the feasibility of implementing the new elleFA app in a clinical setting for 6 months in pre-menopausal women 18 years and older with endometriosis, and the app's impact on patient experience. Participants will download the elleFA app on their smartphone and will be asked to complete two questionnaires through the app every month for 6 months. Participants can choose to also optionally track their daily symptoms, lifestyle, and treatments, through weekly symptom log summaries through the app. The main study finding will be be patient adherence to using the app over a 6 month study period. Other findings will include user-reported satisfaction with the elleFA app, and the impact of elleFA app use on patient experience communicating with their healthcare team.