Summarie is an open-source application designed to summarize documents, utilizing technologies like Next.js 15 and the Ragie TypeScript client to allow users to upload various file types and obtain detailed summaries. The setup involves creating a Next.js project, installing the Ragie SDK, and configuring API routes to handle file uploads securely without exposing API keys. The application includes features such as a simple file upload interface, a backend API for processing files with Ragie, and a mechanism to track document status using polling and webhooks. Once documents reach a "ready" state, summaries are automatically generated and displayed. The app emphasizes best practices including file validation, error handling, and user experience enhancements like progress indicators and feedback on uploads. While the example serves document summarization, the Ragie platform supports broader AI use cases, and the complete code is available in an open-source repository on GitHub.