Resend is an email API and marketing email platform designed to help developers integrate reliable email delivery into websites, applications, and business workflows. The software provides REST APIs, SMTP support, and SDKs for programming languages such as JavaScript, Python, Ruby, PHP, Go, Java, and .NET. Developers can send transactional emails for user authentication, account notifications, purchase confirmations, password resets, and other application-generated events. Its email sending capabilities include batch delivery, scheduled messages, file attachments, and configurable sending domains. React Email integration allows developers to create reusable email templates using React components rather than manually building complex HTML layouts. Resend also includes a visual email editor for creating marketing campaigns, newsletters, and promotional messages without writing code. Audience management tools support contact imports, contact attributes, segmentation, and broadcast email distribution. The platform provides delivery analytics, open and click tracking, bounce notifications, webhook events, and detailed API logs for monitoring email performance. Additional capabilities include domain verification, deliverability insights, dedicated IP addresses, inbound email processing, and automated email workflows.