Inclusion Criteria:  Current, regular user of nicotine e-cigarettes (20+ days in the last month) Exclusive e-cigarette user (no other tobacco in the last 30 days; or no other tobacco in the last 90 days if smoked 100+ cigarettes or cigarillos in lifetime) Interest in quitting in the next 30 days Ownership of a smartphone device Ability to speak and read English  Exclusion Criteria:  Pregnant or breastfeeding Individuals with schizophrenia or bipolar disorder who do not report that their condition is currently effectively managed Individuals who have experienced a heart attack or stroke in the two weeks prior, or who have been diagnosed with rapid/irregular heartbeat or angina in the six months prior to taking the eligibility screener Other household members in study