Peer grading is widely used in high education as effective active learning but still faces challenges. We present the peer grading approach for Open-ended Programming Projects based on the binary and Swiss systems. First, we design a grading specification to improve the accuracy of scoring. Second, to make grading easier for inexperienced students, we utilize a pairwise comparison system based on the binary system. Third, we propose a score calculation algorithm based on Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) to improve grading accuracy. We developed an online peer review tool called Peer Review Studio (PRS) based on the approach. We carry out the method in the undergraduate programming course of 2023. We collect and analyze the learning data between 2022 and 2023. When measured by Krippendorff’s alpha, the inter-rater reliability between instructor and peer grading is in good agreement. When measured by Kruskal-Wallis, students’ project performance and learning engagement significantly improve in the first year of peer grading. The course questionnaire 2023 shows that most students approve of the peer review approach.