HemI is a toolkit for illustrating heatmaps, developed to facilitate the visualization and manipulation of gene or protein expression data. It allows users to create, customize, and export publication-quality heatmaps. The tool supports various clustering strategies and offers options for recoloring, rescaling, and rotating heatmaps. HemI is implemented in Java and can be accessed online. The software is user-friendly, with a simple interface that enables users to load data, select visualization areas, and adjust heatmap parameters. Users can also export heatmaps in different formats and resolutions. The tool was tested on multiple operating systems and is suitable for both bioinformaticians and experimentalists. HemI provides a convenient solution for visualizing and analyzing multi-dimensional data, offering a more efficient alternative to existing tools. The software is continuously maintained and improved based on user feedback. The toolkit was developed to address the limitations of existing tools, such as the need for programming skills and the lack of customization options. HemI allows users to generate and manipulate heatmaps with ease, making it a valuable resource for researchers in the field of bioinformatics.HemI is a toolkit for illustrating heatmaps, developed to facilitate the visualization and manipulation of gene or protein expression data. It allows users to create, customize, and export publication-quality heatmaps. The tool supports various clustering strategies and offers options for recoloring, rescaling, and rotating heatmaps. HemI is implemented in Java and can be accessed online. The software is user-friendly, with a simple interface that enables users to load data, select visualization areas, and adjust heatmap parameters. Users can also export heatmaps in different formats and resolutions. The tool was tested on multiple operating systems and is suitable for both bioinformaticians and experimentalists. HemI provides a convenient solution for visualizing and analyzing multi-dimensional data, offering a more efficient alternative to existing tools. The software is continuously maintained and improved based on user feedback. The toolkit was developed to address the limitations of existing tools, such as the need for programming skills and the lack of customization options. HemI allows users to generate and manipulate heatmaps with ease, making it a valuable resource for researchers in the field of bioinformatics.