OfficeIMO — Open XML utilities for .NET (Word, Excel, PowerPoint, Visio)

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OfficeIMO is a family of lightweight, cross‑platform .NET libraries that make working with Office file formats easier using the Open XML SDK — no Office/COM required.

Word: create and edit .docx documents with a friendly API
Excel: fast read/write helpers, tables, styles, ranges, fluent composers
PowerPoint: build .pptx slides programmatically
Visio: basic .vsdx diagrams

Each project ships as its own NuGet package under the MIT license.

Project READMEs

Word → OfficeIMO.Word/README.md
Excel → OfficeIMO.Excel/README.md
PowerPoint → OfficeIMO.PowerPoint/README.md
Visio → OfficeIMO.Visio/README.md
Converters:
- OfficeIMO.Word.Html — HTML ↔ Word
- OfficeIMO.Word.Markdown — Markdown ↔ Word
- OfficeIMO.Word.Pdf — PDF export for Word

Targets

Word, PowerPoint, Visio: netstandard2.0, net472, net8.0 (Linux/macOS: net8.0); select projects also net9.0
Excel: netstandard2.0, net472, net48, net8.0/net9.0 (cross‑platform)

Build & Coverage

CI (Windows/Linux/macOS): single workflow badge above
Coverage: Codecov dashboard linked above

Licenses

All OfficeIMO packages are MIT‑licensed with exception of Visio which is not yet licensed. See individual project READMEs for third‑party dependency licenses (Open XML SDK, ImageSharp, AngleSharp, QuestPDF, SkiaSharp, etc.).

Dependencies at a glance

Below are product‑centric graphs. Arrows point from a package to what it depends on.

Word

flowchart TB
  WCore[OfficeIMO.Word]
  subgraph Extensions
    WHtml[OfficeIMO.Word.Html]
    WMd[OfficeIMO.Word.Markdown]
    WPdf[OfficeIMO.Word.Pdf]
  end

  %% External deps
  Angle[AngleSharp]
  AngleCss[AngleSharp.Css]
  OfficeIMO.Markdown
  Quest[QuestPDF]
  Skia[SkiaSharp]

  %% Core to extensions (install these when you need that capability)
  WCore --> WHtml
  WCore --> WMd
  WCore --> WPdf

  %% Extension uses
  WMd --> WHtml

  %% External dependencies per extension
  WHtml --> Angle
  WHtml --> AngleCss
  WMd   --> OfficeIMO.Markdown
  WPdf  --> Quest
  WPdf  --> Skia

Converters (Word.Html, Word.Markdown, Word.Pdf) are actively developed and will be released to NuGet once quality and test coverage goals are met. They ship in‑repo for early evaluation.

Excel

flowchart TD
  Xl[OfficeIMO.Excel]
  OXml[DocumentFormat.OpenXml]
  ImgSharp[SixLabors.ImageSharp]
  Fonts[SixLabors.Fonts]

  Xl --> OXml
  Xl --> ImgSharp
  Xl --> Fonts

PowerPoint

flowchart TD
  Ppt[OfficeIMO.PowerPoint]
  OXml[DocumentFormat.OpenXml]

  Ppt --> OXml

Visio

flowchart TD
  Vsdx[OfficeIMO.Visio]
  ImgSharp[SixLabors.ImageSharp]
  Pkg[System.IO.Packaging]

  Vsdx --> ImgSharp
  Vsdx --> Pkg

When do I need what?

Only editing/creating Word (.docx): add OfficeIMO.Word.
Word → PDF export: add OfficeIMO.Word + OfficeIMO.Word.Pdf (pulls QuestPDF + SkiaSharp).
Word ↔ HTML: add OfficeIMO.Word + OfficeIMO.Word.Html (pulls AngleSharp + AngleSharp.Css).
Word ↔ Markdown: add OfficeIMO.Word + OfficeIMO.Word.Markdown (uses OfficeIMO.Markdown and OfficeIMO.Word.Html).
Excel read/write, tables, styles: add OfficeIMO.Excel (pulls ImageSharp + Fonts for sizing and header images).
PowerPoint slides: add OfficeIMO.PowerPoint.
Visio drawings: add OfficeIMO.Visio (uses ImageSharp and System.IO.Packaging).

Dependency versions (high‑level)

DocumentFormat.OpenXml: 3.3.x (constraints: [3.3.0, 4.0.0))
SixLabors.ImageSharp: 2.1.x; SixLabors.Fonts: 1.0.x (Excel)
AngleSharp: 1.3.x; AngleSharp.Css: 1.0.0‑beta.154 (Word.Html)
QuestPDF: 2025.7.x; SkiaSharp: 3.119.x (Word.Pdf)

We keep package ranges conservative to avoid breaking changes; see each project’s csproj for exact ranges.

Licenses

OfficeIMO.Word, OfficeIMO.Excel, OfficeIMO.PowerPoint, OfficeIMO.Word.Html, OfficeIMO.Word.Markdown, OfficeIMO.Word.Pdf: MIT
OfficeIMO.Visio: License TBD (not MIT yet)

Third‑party dependency licenses: see their upstream repos (Open XML SDK, SixLabors, AngleSharp, QuestPDF, SkiaSharp).

Support This Project

If you find this project helpful, please consider supporting its development. Your sponsorship will help the maintainers dedicate more time to maintenance and new feature development for everyone.

It takes a lot of time and effort to create and maintain this project. By becoming a sponsor, you can help ensure that it stays free and accessible to everyone who needs it.

To become a sponsor, you can choose from the following options:

Your sponsorship is completely optional and not required for using this project. We want this project to remain open-source and available for anyone to use for free, regardless of whether they choose to sponsor it or not.

If you work for a company that uses our .NET libraries or PowerShell modules, please consider sponsoring. Thank you for considering support!