nissl-lab/npoi

a .NET library that can read/write Office formats without Microsoft Office installed. No COM+, no interop.

C#

6,201

3,934 commits

updated Oct 9, 2026

See the code

README

NuGet Nuget Ranking! Discord License EULA traffic Github contributors

[!IMPORTANT] To ensure the long-term sustainability of this project, a monthly maintenance fee has been introduced. This fee is required to be paid by all organizations or users of any library from this project who generate revenue. You can pay the fee via GitHub Sponsors.

To enact this, an EULA on binary releases is added to the repo and nuget packages since 2.8.0 that requires payment of the maintenance fee.

For more information on who must pay the fee and other frequently asked questions, please see the Open Source Maintenance Fee organisation page.

What's NPOI

This project is the .NET version of Apache POI project. With NPOI, you can read/write Office 2003/2007 files very easily.

Documentation

NPOI Official Tutorials

Getting Started with NPOI

How NPOI library succeeds

How to use NPOI on Linux

Useful Packages based on NPOI

Sponsors

Thank you for all the sponsors. Here is the sponsors list

Advantage of NPOI

a. It's totally free to startups, freelancers, and hobbyists (whose annual revenue is less than $10,000 USD)

b. Cover most features of Excel (cell style, data format, formula and so on)

c. Supported formats: xls, xlsx, docx.

d. Designed to be interface-oriented (take a look at NPOI.SS namespace)

e. Support not only export but also import

f. Real successful cases all over the world

g. Works on both Windows and Linux

System Requirement

.NET 8

.NET Standard 2.1 (.NET Core 3.x, .NET 5, .NET 6)

.NET Standard 2.0 (.NET Core 2.x)

.NET Framework 4.0 and above

Contributors

Contributors

Flag Counter

biff
dotnetcore
excel
office-file-api
openxml
poi
word

nissl-lab/npoi

a .NET library that can read/write Office formats without Microsoft Office installed. No COM+, no interop.

C#

6,201

3,934 commits

updated Oct 9, 2026

See the code

README

NuGet Nuget Ranking! Discord License EULA traffic Github contributors

[!IMPORTANT] To ensure the long-term sustainability of this project, a monthly maintenance fee has been introduced. This fee is required to be paid by all organizations or users of any library from this project who generate revenue. You can pay the fee via GitHub Sponsors.

To enact this, an EULA on binary releases is added to the repo and nuget packages since 2.8.0 that requires payment of the maintenance fee.

For more information on who must pay the fee and other frequently asked questions, please see the Open Source Maintenance Fee organisation page.

What's NPOI

This project is the .NET version of Apache POI project. With NPOI, you can read/write Office 2003/2007 files very easily.

Documentation

NPOI Official Tutorials

Getting Started with NPOI

How NPOI library succeeds

How to use NPOI on Linux

Useful Packages based on NPOI

Sponsors

Thank you for all the sponsors. Here is the sponsors list

Advantage of NPOI

a. It's totally free to startups, freelancers, and hobbyists (whose annual revenue is less than $10,000 USD)

b. Cover most features of Excel (cell style, data format, formula and so on)

c. Supported formats: xls, xlsx, docx.

d. Designed to be interface-oriented (take a look at NPOI.SS namespace)

e. Support not only export but also import

f. Real successful cases all over the world

g. Works on both Windows and Linux

System Requirement

.NET 8

.NET Standard 2.1 (.NET Core 3.x, .NET 5, .NET 6)

.NET Standard 2.0 (.NET Core 2.x)

.NET Framework 4.0 and above

Contributors

Contributors

Flag Counter

biff
dotnetcore
excel
office-file-api
openxml
poi
word

Project health

NuGet

Latest release

2.8.1 · Sep 22, 2026

Releases this year

3

Significant stargazers

Oleksii Holub

2,961 followers · starred Aug 2017

Erik Schierboom

600 followers · starred Jun 2015

Muhammad Azeez

197 followers · starred Apr 2022

Opportunity

213 followers · starred Sep 2019