Online questionnaires are questionnaires that are administered over the internet to gather data about behaviour, experiences, attitudes, beliefs and values. They are used as a research method within a variety of methodologies including survey research (Mei and Brown, 2018), grounded theory (Jenkins et al., 2015) and ethnography (Murthy, 2008), and can be used as a standalone method (Cumming et al., 2007) or combined with other online or offline methods (Kamalodeen and Jameson-Charles, 2016). There are three basic types of online questionnaire: closed-ended (used to generate statistics in quantitative, survey research), open-ended (used in qualitative research to gather in-depth attitudes and opinions) or a combination of both (used to generate statistics and explore ideas, beliefs and/or experiences). Questionnaires can be embedded into websites or blogs, sent out as a bulk email to targeted groups (as attachments or unique links), shared on social networks or as QR Codes (Quick Response Codes) for respondents to scan with their mobile devices, for example. Online questionnaires can also be referred to as web-based questionnaires, web questionnaires, electronic questionnaires or e-questionnaires.