# dotnetcore/NPOI

A .NET library for reading and writing Microsoft Office binary and OOXML file formats.

Repository: https://github.com/dotnetcore/NPOI
Canonical: https://ross.abutalabs.com/products/dotnetcore-npoi
Language: C#
License: Apache-2.0
License Family: permissive
Topics: npoi, word, excel, office
Archived: true
Last push: 2020-11-24T05:18:22+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 3561, "days_push": 2108, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1950, forks 406 (observed 2026-08-28T04:05:58.191725+00:00)

## What it is
NPOI is a .NET library for reading and writing Microsoft Office binary (BIFF) and OOXML file formats such as Excel and Word documents. It is a .NET Core port of the Apache POI project, migrated from Tony Qu's original NPOI.

## Use cases
- read and write Excel xlsx files in C#
- generate Word documents programmatically in .NET
- parse legacy .xls binary spreadsheets
- export data grids to Excel without Office installed
- manipulate Office OOXML files on .NET Core
- create Excel reports from a web application

## When to choose
- you need to read or write Excel/Word files in .NET without COM interop or Office installed
- you need support for both legacy binary (.xls) and OOXML (.xlsx/.docx) formats
- you want a free Apache-2.0 alternative to commercial spreadsheet libraries

## When to avoid
- you need a fully managed, actively maintained alternative and prefer ClosedXML or Open XML SDK for xlsx only
- you need formats beyond Office files like PDF or ODF
- you require very heavy Excel features like full chart rendering

## Facets
- artifact type: library
- maturity: maintenance
- function: parser, file-system, serialization
- domain: files, developer-tools, spreadsheets
- platform: dotnet, cross-platform
- tags: excel, word, office-formats, ooxml, xlsx, docx, spreadsheet, apache-poi-port

## Member repositories
- dotnetcore/NPOI (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:58.191725+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:06:51.478273+00:00, confidence not recorded.
  - readme: https://github.com/dotnetcore/NPOI (fetched 2026-08-28T04:05:58.191725+00:00, sha 113406910f12)
- Data as of 2026-08-30T08:39:29.467469+00:00.