Heml is an easy-to-use toolkit for creating and manipulating heatmaps, designed to visualize gene or protein expression data. It supports various clustering strategies and allows for recoloring, rescaling, and rotation of heatmaps. The tool is implemented in Java and can export publication-quality figures. Heml addresses the limitations of existing tools by providing a user-friendly interface and robust functionality, making it a valuable resource for both bioinformaticians and experimentalists. The software is freely available at http://hemi.biocuckoo.org/down.php.Heml is an easy-to-use toolkit for creating and manipulating heatmaps, designed to visualize gene or protein expression data. It supports various clustering strategies and allows for recoloring, rescaling, and rotation of heatmaps. The tool is implemented in Java and can export publication-quality figures. Heml addresses the limitations of existing tools by providing a user-friendly interface and robust functionality, making it a valuable resource for both bioinformaticians and experimentalists. The software is freely available at http://hemi.biocuckoo.org/down.php.