Participants
RECRUITMENT
Recruitment took place in two different settings. First, online advertisement (Google, Bing, and Facebook) was used to recruit individuals seeking help to quit smoking. Individuals clicking on the advert were taken to the study website which contained study information and instructions on how to sign up. Second, health care professionals at 54 participating primary health care units in the south of Sweden advertised the trial to patients through printed media (e.g. flyers, leaflets, business cards, posters). Like the website, the printed media contained study information and instructions on how to sign up. Regardless of setting, individuals were instructed sign up for the trial by sending a text message to a dedicated telephone number. Within 5 min, they received a text message in response, with a hyperlink to study information and an informed consent form.Participants consenting to take part in the trial were immediately redirected to a baseline questionnaire, after which eligible participants were randomised. Individuals aged 18 years or older who smoked at least 1 cigarette per week were eligible for the trial. Most of the study information, and all questionnaires, were delivered to participants through their mobile phone and was in Swedish; thus, participants without access to a mobile phone and who did not comprehend Swedish well enough to sign up for the trial were excluded.