This corpus is a collection of open peer reviews and related data from the MDPI publisher. It covers more than 135,000 papers published on mdpi.com as of January 2023. The corpus includes the plain text of the reviews, the author responses, and the paper metadata in JSON format. It also includes the HTML source of the web pages where the reviews were extracted from, and any supplementary materials attached to the reviews, such as PDF and DOCX files. The corpus is a valuable resource for studying the peer review process, the quality and impact of scientific publications, and the linguistic features of academic discourse.