At St Andrews the ethics committee UTREC (University Teaching and Research Ethics Committee) recommends the use of qualtrics for online surveys.
They also acknowledge the fact that the longer information sheets and consent forms used in face-to-face research are often not appropriate in an online context. To accommodate that, UTREC discuss the key ethical issues that apply to online research and make some suggestions about the form that the information and consent section of a questionnaire should look like.
You can find the UTREC statement about the use of online surveys here.