Version 4.5.3.3 is the last version of EPPlus you can use without a license for commercial use.
We now have a blog series on an alternative Excel package ClosedXML
Which is basically on equal footing with EPPlus.
EPPlus Repositories
JanKallman/EPPlus: The old and free one 
EPPlusSoftware/EPPlus: The new and not so free one
Forks
EPPlus is a pretty solid tool and you probably don’t need any of the additional fluff they’re adding in the now paid version. Use these to circumvent the official EPPlus misleading “Deprecated” notice.
rimland/EPPlus: Most stars but no activity in the last 5 years 
visualon/epplus: Actively maintained up till .NET 8 support but deprecated since May 28, 2025
One thing that I did stumble upon with the classic EPPlus is that it has a dependency on System.Drawing.Common which only works on Windows. The non-free version has removed this dependency.
Alternatives
If you prefer something that is more actively maintained/developed:
ClosedXML/ClosedXML: .NET library for reading, manipulating and writing Excel files 
nissl-lab/npoi: .NET library to read/write Office formats 
mini-software/MiniExcel: Easy Excel .NET helper to import/export/template spreadsheets 
mganss/ExcelMapper: An Excel to object mapper.
If you just need to read
ExcelDataReader/ExcelDataReader: Lightweight C# library for reading Excel files
Low Level
Very low level and verbose. What EPPlus and ClosedXML use under the hood.
dotnet/Open-XML-SDK: Open XML SDK by Microsoft.
Also in this series
- Part 1: Create Excels with C# and EPPlus: A tutorial
- Part 2: Create Excels with C# and EPPlus: Formulas & DataValidation
- Part 3: Create Excels with C# and EPPlus: Import
- Part 4: Create Excels with C# and EPPlus: Miscellaneous
- Part 5: Excel formulas cheat sheet
- This Part: EPPlus: No longer free to use in a commercial setting
Updates
- 25 February 2025: Added EPPlus forks
Package Versions
JanKallman/EPPlus: v4.5.3.3 EPPlus-Commercial: v5.0.3