# nissl-lab/npoi

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

Repository: https://github.com/nissl-lab/npoi
Canonical: https://ross.abutalabs.com/products/npoi
Homepage: http://nissl-lab.github.io/npoi/
Language: C#
License: Apache-2.0
License Family: permissive
Topics: excel, biff, openxml, word, poi, dotnetcore, office-file-api
Last push: 2026-08-24T14:06:40+00:00

## Health v2 (maintenance only)
Score: 83/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 53, longevity 100
- inputs: {"age_days": 4992, "days_push": 9, "days_rel": 152, "gap_med": 102, "n_releases_24m": 6}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 6191, forks 1491 (observed 2026-08-28T04:09:39.144076+00:00)

## What it is
NPOI is a .NET library, a port of Apache POI, that reads and writes Office file formats (xls, xlsx, docx) without requiring Microsoft Office or COM interop. It supports cell styles, data formats, and formulas, and works across Windows and Linux on .NET Framework, .NET Standard 2.0/2.1, and .NET 8.

## Use cases
- generate excel reports from .net without office installed
- read xlsx files in a .NET Core app on Linux
- export data to xls spreadsheets from ASP.NET
- import excel data into a database with C#
- create Word docx documents programmatically in .NET
- manipulate excel formulas and cell styles without COM interop

## When to choose
- you need to read/write Excel or Word files in .NET without installing Microsoft Office
- you need cross-platform (Linux/Windows) Office file processing
- you need support for legacy xls (BIFF) and modern xlsx formats
- you want a free option as a startup, freelancer, or hobbyist

## When to avoid
- your organization generates revenue and you cannot accept the Open Source Maintenance Fee EULA on binaries since 2.8.0
- you need Office formats beyond xls/xlsx/docx (e.g., pptx)
- you prefer a fully permissive license with no revenue-based fees

## Facets
- artifact type: library
- maturity: active
- function: serialization, file-system, developer-tools
- domain: files, spreadsheets, developer-tools, cross-platform
- platform: dotnet, cross-platform, windows
- tags: excel, openxml, biff, word, office-formats, no-interop, apache-poi-port, spreadsheet, linux, macos

## Member repositories
- nissl-lab/npoi (main) score 83

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:39.144076+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 2026-08-29T17:47:22.293984+00:00, confidence not recorded.
  - readme: https://github.com/nissl-lab/npoi (fetched 2026-08-28T04:09:39.144076+00:00, sha 6cd1e3c20b63)
  - homepage: http://nissl-lab.github.io/npoi/ (fetched 2026-08-29T08:43:51.703573+00:00, sha 6ade58115881)
- Data as of 2026-08-30T08:39:29.467469+00:00.