A practical comparison of seven C# Word libraries for .NET developers in 2026, covering IronWord, Open XML SDK, Aspose.Words, DocX/Xceed, Spire.Doc, Syncfusion DocIO, and NPOI. Each library is evaluated on DOCX read/write, legacy .doc support, Word-to-PDF conversion, mail-merge, licensing terms, and commercial use restrictions. Key findings: Open XML SDK is the only fully unrestricted MIT option but requires verbose code; Aspose.Words leads on format conversion fidelity; DocX is commonly misused commercially due to its non-commercial-only community license; NPOI v2.8.0 introduced a paid maintenance fee EULA for binary packages. Recommendations are scenario-driven, with IronWord suggested for general-purpose cross-platform DOCX generation, Aspose.Words for conversion-heavy workloads, and Open XML SDK for regulated/audit-sensitive environments.
Table of contents
Why C# Word Library Selection Matters1. IronWord2. Open XML SDK3. Aspose.Words4. DocX / Xceed DocX5. Spire.Doc6. Syncfusion DocIO7. NPOIFeature Comparison MatrixCommon Use Cases and RecommendationsEmerging TrendsPerformance ConsiderationsBest PracticesMigration StrategiesConclusion1 Comment
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