Creating and Reading Excel Files: Formatted Reports with ClosedXML, Large Exports and the EPPlus License
Produce formatted reports with ClosedXML; write dates as DateTime, ISBNs as text and money through number formats, render into memory and send with filename* in Content-Disposition. For large exports ClosedXML uses 368 MB at 100,000 rows and OpenXmlWriter 56 MB, but System.IO.Packaging pushes the latter to 583 MB at a million; SpreadCheetah stays at 8 MB. EPPlus needs a per-developer license for commercial use.
15 Nov 2026
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13 min
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