EPPlus

EPPlus is one of the most widely used libraries for reading and writing Excel .xlsx files in .NET — worksheets, formulas and a calculation engine, pivot tables, charts, conditional formatting, and import/export from data tables and collections. It works directly on the Open XML format, with no dependency on Excel or interop.

EPPlus was LGPL for its first decade. With version 5 — first stable release 8 March 2020 — it moved to a dual license: Polyform Noncommercial 1.0.0 as the community license, plus a paid commercial license for any business use. This is the oldest change tracked on this site, and the one most likely to already be sitting undetected in a legacy codebase.

What Changed

• EPPlus 4.5.3.3 (published 30 January 2020) is the last LGPL release. It remains freely usable, including commercially, under LGPL terms.
• EPPlus 5 and later are licensed Polyform Noncommercial for free use, or commercially for everything else. The source is still published on GitHub — but Polyform Noncommercial is not an open-source license: it permits use only for noncommercial purposes.

Free use under Polyform Noncommercial covers personal use for research, experiment, personal study and hobby projects, and noncommercial organizations such as charities, education, and public research, safety or health bodies. Anything done by or for a business — including internal line-of-business tools that are never sold — requires a commercial license.

The license must be declared in code

EPPlus is one of the few libraries here with a runtime gate: if you do not declare a license, it throws a LicenseException.

• EPPlus 5 – 7: set the license context once at startup.

  ExcelPackage.LicenseContext = LicenseContext.NonCommercial; // or .Commercial
  

• EPPlus 8 (first stable 8.0.1, 28 March 2025) replaced LicenseContext with an explicit license API and introduced license keys for commercial use:

  ExcelPackage.License.SetNonCommercialPersonal("Your Name");
  ExcelPackage.License.SetNonCommercialOrganization("Your Organization");
  ExcelPackage.License.SetCommercial("<your-license-key>");
  

  Upgrading from 7 to 8 is therefore a breaking change for every project, regardless of tier.

Who Pays and How Much

Commercial licensing is per developer, with unlimited deployment. Published USD prices:

Perpetual licenses start at $899 per developer with one year of support and upgrades ($1,339 for two years), keeping permanent rights to every version released during the support period. Bulk license packages run from $6,395 (up to 10 developers, 1 year) to $15,145 (up to 25 developers, 2 years). Prices are per developer per year and exclude local tax — check the official page before budgeting.

What This Means For You

• Hobby project, study, charity, school, or public research: free — declare the noncommercial license in code and you are done.
• Any commercial company, including internal-only tools: you need a paid license from $329–$569 per developer per year. "We don't sell the spreadsheet" is not an exemption.
• Still on EPPlus 4.x: you are on LGPL and owe nothing — but you are also five years behind on fixes and new Excel features.
• Upgrading 7 → 8: budget for the LicenseContext → License.Set* code change and, for commercial users, license-key distribution to build agents and developers.

Caution: unofficial repackages of the last LGPL release circulate on NuGet under names like EPPlusFree and EPPlus-LGPL. They are not published by EPPlus Software; treat them with the scrutiny you would give any third-party republish of someone else's library.

Alternatives

1. Pin EPPlus 4.5.3.3:

   • The last LGPL release, free for commercial use under LGPL terms.
   • Pros: no code change, no fee, well understood.
   • Cons: unmaintained since January 2020 — no security fixes, no new Excel features, no new .NET target support. LGPL also brings its own obligations if you modify it.

2. ClosedXML:

   • MIT, the most common escape route from EPPlus. A friendly wrapper over the Open XML SDK with a similar mental model (workbooks, worksheets, cells, styles) and a formula engine.
   • Pros: free for any use, active, large community, closest API ergonomics to EPPlus.
   • Cons: higher memory use on large workbooks; pivot table and chart support is narrower than EPPlus.

3. MiniExcel:

   • Apache-2.0, streaming-first. Reads and writes without loading the whole document into memory.
   • Pros: free, dramatically lower memory and faster on large files, simple query/insert API.
   • Cons: deliberately minimal — little styling, no charts, no calculation engine. A data-pipeline tool, not a spreadsheet-authoring one.

4. Open XML SDK (DocumentFormat.OpenXml):

   • MIT, maintained by Microsoft — the first-party foundation the others build on.
   • Pros: free, authoritative, complete format coverage, no third-party risk.
   • Cons: very low-level; simple tasks take a lot of code. Best when you need guarantees rather than convenience.

5. NPOI:

   • Apache-2.0 source, and historically the standard free alternative — but as of 2.8.0 its binary releases carry an Open Source Maintenance Fee. Swapping EPPlus for NPOI to avoid a fee no longer works cleanly; read the NPOI page first.

For write-only reporting workloads, SpreadCheetah (MIT) and LargeXlsx (BSD) are fast, low-allocation options.

Conclusion

EPPlus 5+ is not open source: it is Polyform Noncommercial plus a per-developer commercial license, from $329–$569 per developer per year, and EPPlus 8 enforces it with a license key and a LicenseException if you say nothing. The last free-for-business release is 4.5.3.3 from January 2020. Teams needing a permissive, maintained Excel library generally land on ClosedXML (closest ergonomics), MiniExcel (large files), or the Open XML SDK (first-party, low-level) — and should note that NPOI, the traditional fallback, now carries a maintenance fee of its own.

Links and References

• EPPlus Software: LGPL to Polyform · License and pricing · License FAQ
• EPPlus Software: EPPlus 8 · Breaking changes in EPPlus 8 · LicenseException
• GitHub: EPPlusSoftware/EPPlus
• NuGet: EPPlus 4.5.3.3 (last LGPL release)
• License: Polyform Noncommercial 1.0.0
• Alternative: ClosedXML · MiniExcel · Open XML SDK
• Related: NPOI