The Dropbox SDK for JavaScript (dropbox-sdk-js) is a lightweight, promise-based client library that provides a programmatic interface to the Dropbox v2 API. It supports both Node.js and browser environments, with full OAuth 2.0/PKCE authentication, file upload and download with resumable and parallel streaming, exponential backoff retries, progress reporting, and content hash validation. The library is auto-generated from Dropbox's API specification (Stone) and exposes hundreds of endpoint methods covering files, sharing, team management, users, and more. It is designed for production use with robust error handling, rate-limit awareness, and environment-aware binary types. The codebase demonstrates strong architectural separation of concerns: authentication logic is encapsulated in `DropboxAuth`, file transfer logic in dedicated uploader/downloader classes, and API request routing in generated route definitions. The SDK is well-tested with unit, integration, and TypeScript type tests, and includes comprehensive examples for both browser and Node.js usage patterns.