Phenol-Explorer is the first comprehensive web-based database on polyphenol content in foods. It contains over 37,000 data points from 638 scientific articles, providing representative mean content values for 502 polyphenols in 452 foods. The database allows users to query data to identify foods containing specific polyphenols or polyphenols present in specific foods. For each mean content value, users can trace all original data points and their sources. The database is accessible via a user-friendly web interface and includes detailed information on polyphenol content, analytical methods, and food composition. It is a major step forward in the development of food constituent databases and the food metabolome. Phenol-Explorer helps researchers understand the role of phytochemicals in food quality and assists food manufacturers in developing healthier foods. The database is open access and includes data from peer-reviewed publications, with a focus on food-based polyphenols. It includes information on the occurrence and content of polyphenols in foods, as well as their biological effects. The database was developed through a systematic process involving literature search, data compilation, evaluation, aggregation, and exportation to a MySQL database. It includes detailed information on foods, polyphenols, analytical methods, and composition. The database allows for simple and advanced searches, including queries on polyphenol content in specific foods or polyphenols in specific foods. It also allows for the addition of new data by authorized compilers. Phenol-Explorer is a valuable resource for food scientists, manufacturers, dieticians, and health professionals to better understand the impact of phytochemicals on health and to develop healthier foods. The database is also expected to be extended to include information on the effects of cooking and processing on polyphenol content and on phytochemical metabolites formed in the body.Phenol-Explorer is the first comprehensive web-based database on polyphenol content in foods. It contains over 37,000 data points from 638 scientific articles, providing representative mean content values for 502 polyphenols in 452 foods. The database allows users to query data to identify foods containing specific polyphenols or polyphenols present in specific foods. For each mean content value, users can trace all original data points and their sources. The database is accessible via a user-friendly web interface and includes detailed information on polyphenol content, analytical methods, and food composition. It is a major step forward in the development of food constituent databases and the food metabolome. Phenol-Explorer helps researchers understand the role of phytochemicals in food quality and assists food manufacturers in developing healthier foods. The database is open access and includes data from peer-reviewed publications, with a focus on food-based polyphenols. It includes information on the occurrence and content of polyphenols in foods, as well as their biological effects. The database was developed through a systematic process involving literature search, data compilation, evaluation, aggregation, and exportation to a MySQL database. It includes detailed information on foods, polyphenols, analytical methods, and composition. The database allows for simple and advanced searches, including queries on polyphenol content in specific foods or polyphenols in specific foods. It also allows for the addition of new data by authorized compilers. Phenol-Explorer is a valuable resource for food scientists, manufacturers, dieticians, and health professionals to better understand the impact of phytochemicals on health and to develop healthier foods. The database is also expected to be extended to include information on the effects of cooking and processing on polyphenol content and on phytochemical metabolites formed in the body.