Introduction: Nutrition counseling web apps have the ability to improve the quality of health care. The purpose of this study is to design and evaluate the usability of a nutrition counseling web app (virtual clinic) for pregnant women.Material and Methods: It was a descriptive-cross-sectional applied study that first designed and then examined the nutritional counseling web app (virtual clinic) for pregnant women using the heuristic evaluation method. The data was collected with a standard form designed based on the heuristic method. Data analysis was done with SPSS version 26.Results: The number of known individual problems was 34. The highest number of problems was related to the flexibility and efficiency component and the lowest number was related to the component of helping users in diagnosing, identifying and correcting errors. In the end, all the problems identified in the web app were solved and it was given to the evaluators again, and in the end, a score of zero was assigned to all the components, meaning no problem.Conclusion: Compliance with existing standards and rules in the design of web app user interfaces, such as the heuristics mentioned in this study, can reduce problems.