Compares three popular .NET libraries for Excel file manipulation: OpenXML SDK, EPPlus, and ClosedXML. OpenXML provides granular control and memory efficiency but requires verbose, low-level XML manipulation. EPPlus offers rich features like charts and pivot tables with cleaner syntax but requires a commercial license. ClosedXML provides the most intuitive API with MIT licensing, ideal for small to medium datasets. Includes working code examples demonstrating how to create Excel files with each library, highlighting their syntax differences and practical tradeoffs.