This digital resource is the Agilent eArray online tool, a web-based application designed for creating and customizing microarray designs. Agilent eArray allows researchers to design custom microarrays for various applications, including gene expression, comparative genomic hybridization (CGH), and microRNA analysis, or to select from Agilent's catalog content. The eArray tool provides a flexible platform where users can input their specific target sequences or select from Agilent's extensive probe databases to generate custom arrays tailored to their research needs. It supports the design of multi-species arrays and offers guidance for optimal design principles, such as incorporating control probes and ensuring proper probe replication for accurate data analysis. This tool is indispensable for researchers who require highly specific and customized microarray content beyond standard catalog offerings. It enables the creation of unique experimental platforms for targeted gene expression profiling, genomic variation studies, and other applications, providing a high degree of control over the experimental design. As a proprietary online service from Agilent, eArray integrates seamlessly with Agilent's SurePrint technology for microarray manufacturing, ensuring that custom designs can be reliably produced with high quality. It is a critical resource for advanced genomics research, allowing for the rapid development and deployment of specialized microarray assays.