To develop and validate a web-based self-diagnostic questionnaire on school food service offer aimed at food service managers (FSM) by: (i) identifying relevant indicators of school food offer, developing a questionnaire and validating the concept using an expert panel; (ii) validating the questions by comparing the FSM’s responses with observations by dietitians and (iii) undergoing a qualitative evaluation of the tool through direct observation and short interviews.

Mixed methods.

Quebec, Canada.

Nine experts validated the theoretical constructs and indicators on which the questionnaire was based. Inter-rater reliability tests were conducted with thirty-nine FSM, who then participated in interviews about platform functionality satisfaction. Twenty school stakeholders participated in the survey pertaining to their use of the personalised report.

The questionnaire focused on the main school food service’s lunchtime offer and comprised twenty-six questions. The overall strength of agreement was good, and all questions’ strengths of agreement were fair to excellent except for one question. Qualitative data reached saturation and showed that navigation through the questionnaire was fluid. Improvements were suggested to increase user-friendliness and simplicity of both the platform and questionnaire. Results from the survey showed that all respondents were either satisfied or very satisfied with their personalised report.

We successfully developed and validated a web-based self-diagnostic questionnaire. The final version facilitates knowledge mobilisation with school stakeholders and offers a new opportunity for the assessment and surveillance of school food offer.