The UK government is due to impose restrictions on junk food adverts to curb children’s exposure to the temptation of HFSS (High in Fat, Salt and Sugar) foods, in the lieu of mounting child obesity. However, there is a lack of evidence that could give us an idea about the extent of children’s exposure to online marketing of food and drinks. In November and December 2021, Nesta carried out a crowdsourcing project in which 284 teenagers aged between 13 and 16 participated. The aim of this project was to find out more about the online food and drink marketing young people see online using the method of crowdsourcing and we use self-reported measure of exposure as a proxy for real exposure. Our key finding shows that 70% of self-reported exposure belongs to the HFSS category.