OfficeIMO - Office and document libraries for .NET

OfficeIMO is a family of COM-free .NET libraries for creating, reading, converting, and exporting Office and document formats. The packages are designed for services, desktop apps, build agents, and automation hosts where Microsoft Office automation is not available or not appropriate.

If OfficeIMO saves you time, please consider supporting the work through GitHub Sponsors or PayPal. Sponsorship helps keep the libraries maintained, tested, and MIT licensed.

PowerShell users should start with EvotecIT/PSWriteOffice, which is the PowerShell-facing project built around OfficeIMO.

Main packages

Package	Purpose
OfficeIMO.Word	Create, edit, inspect, and convert .docx documents, with first-party support for a tested legacy .doc subset.
OfficeIMO.Excel	Create and modify .xlsx workbooks, open legacy .xls workbooks, worksheets, tables, ranges, styles, and reports.
OfficeIMO.PowerPoint	Generate .pptx presentations programmatically.
OfficeIMO.Visio	Create, inspect, validate, and export .vsdx diagrams without Visio automation.
OfficeIMO.Pdf	Dependency-free PDF creation, reading, inspection, page operations, and converter engine support.
OfficeIMO.OpenDocument	Native ODT, ODS, and ODP creation, editing, inspection, and preservation.
OfficeIMO.Rtf	Bounded RTF parser, lossless syntax tree, editable semantic model, writer, and conversion reports.
OfficeIMO.Markdown	Typed Markdown AST, builder API, reader, and HTML renderer.
OfficeIMO.Reader	Unified read-only extraction facade with modular adapters.

Converters and adapters

Package	Purpose
OfficeIMO.Word.Html	Word to/from HTML conversion.
OfficeIMO.Word.Markdown	Word to/from Markdown conversion.
OfficeIMO.Word.Pdf	Word to PDF through OfficeIMO.Pdf.
OfficeIMO.Word.OpenDocument	Explicit Word/ODT conversion with feature-mapping reports.
OfficeIMO.Word.Rtf	Result-bearing Word/RTF conversion, mail merge, fields, merge, and comparison workflows.
OfficeIMO.Excel.Pdf	Excel workbook to PDF through OfficeIMO.Pdf.
OfficeIMO.Excel.OpenDocument	Explicit Excel/ODS conversion with bounded sparse expansion and feature-mapping reports.
OfficeIMO.PowerPoint.Pdf	PowerPoint presentation to PDF through OfficeIMO.Pdf.
OfficeIMO.PowerPoint.OpenDocument	Explicit PowerPoint/ODP conversion with feature-mapping reports.
OfficeIMO.Markdown.Html	HTML to Markdown document conversion.
OfficeIMO.Markdown.Pdf	Markdown to PDF through OfficeIMO.Pdf.
OfficeIMO.Html.Pdf	Direct HTML-to-PDF rendering and PDF-to-HTML projection.
OfficeIMO.Html	Shared HTML parsing, resource policy, layout, PNG/SVG rendering, and HTML-to/from-RTF.
OfficeIMO.Rtf.Pdf	Visual RTF-to-PDF export and extractive PDF-to-RTF import.

Markdown, markup, and rendering

Package	Purpose
OfficeIMO.Markup	Markdown-inspired semantic authoring model for OfficeIMO documents.
OfficeIMO.Markup.Word	Render markup documents to Word.
OfficeIMO.Markup.Excel	Render markup documents to Excel workbooks.
OfficeIMO.Markup.PowerPoint	Render markup documents to PowerPoint presentations.
OfficeIMO.Markup.Cli	CLI parser, validator, preview, and code-emission tooling.
OfficeIMO.MarkdownRenderer	Browser/WebView-friendly Markdown rendering shell.
OfficeIMO.MarkdownRenderer.Wpf	WPF/WebView2 Markdown host control.
OfficeIMO.MarkdownRenderer.IntelligenceX	IntelligenceX renderer feature pack.
OfficeIMO.MarkdownRenderer.SamplePlugin	Sample third-party-style renderer plug-in package.

Reader family

Package	Purpose
OfficeIMO.Reader	Common extraction model and folder/stream helpers.
OfficeIMO.Reader.Csv	CSV/TSV reader adapter.
OfficeIMO.Reader.Epub	EPUB reader adapter.
OfficeIMO.Reader.Html	HTML reader adapter.
OfficeIMO.Reader.Json	JSON reader adapter.
OfficeIMO.Reader.OpenDocument	Native ODT, ODS, and ODP reader adapter.
OfficeIMO.Reader.Ocr.Process	Optional versioned external-process OCR provider.
OfficeIMO.Reader.Ocr.Tesseract	Optional Tesseract CLI OCR provider.
OfficeIMO.Reader.Pdf	PDF reader adapter.
OfficeIMO.Reader.Rtf	Bounded RTF chunks, tables, visuals, warnings, and provenance.
OfficeIMO.Reader.Visio	Visio inspection snapshot adapter.
OfficeIMO.Reader.Xml	XML reader adapter.
OfficeIMO.Reader.Yaml	YAML reader adapter.
OfficeIMO.Reader.Zip	ZIP traversal reader adapter.

Google Workspace and primitives

Package	Purpose
OfficeIMO.GoogleWorkspace	Shared Google Workspace credentials, sessions, retry, Drive location, and translation reporting.
OfficeIMO.Word.GoogleDocs	Word to Google Docs planning and export scaffolding.
OfficeIMO.Excel.GoogleSheets	Excel to Google Sheets planning and export scaffolding.
OfficeIMO.CSV	Fluent CSV document model.
OfficeIMO.Drawing	Shared color, image, font, and drawing primitives.
OfficeIMO.Zip	Safe ZIP traversal primitives.
OfficeIMO.Epub	EPUB extraction primitives.

Install

Install only the packages you need:

dotnet add package OfficeIMO.Word
dotnet add package OfficeIMO.Excel
dotnet add package OfficeIMO.PowerPoint
dotnet add package OfficeIMO.OpenDocument
dotnet add package OfficeIMO.Pdf

Converter packages are intentionally separate so applications can opt into the extra dependency surface only when needed:

dotnet add package OfficeIMO.Word.Pdf
dotnet add package OfficeIMO.Word.OpenDocument
dotnet add package OfficeIMO.Excel.Pdf
dotnet add package OfficeIMO.Excel.OpenDocument
dotnet add package OfficeIMO.PowerPoint.OpenDocument
dotnet add package OfficeIMO.Markdown.Pdf

Quick example

using OfficeIMO.Word;

using var document = WordDocument.Create("report.docx");
document.AddParagraph("OfficeIMO").SetBold();
document.AddParagraph("Created without Microsoft Office automation.");
document.Save();

Common workflows

Create an Excel report

using OfficeIMO.Excel;

using var workbook = ExcelDocument.Create("sales.xlsx");
var sheet = workbook.AddWorksheet("Sales");

sheet.CellValue(1, 1, "Product");
sheet.CellValue(1, 2, "Revenue");
sheet.CellValue(2, 1, "Alpha");
sheet.CellValue(2, 2, 120);
sheet.CellValue(3, 1, "Beta");
sheet.CellValue(3, 2, 92);
sheet.AddTable("A1:B3", hasHeader: true, name: "SalesTable", style: TableStyle.TableStyleMedium2);
sheet.AutoFitColumns();

workbook.Save();

Parse CSV into typed objects

using OfficeIMO.CSV;

List<Person> people = CsvDocument.Load("people.csv")
    .EnsureSchema(schema => schema
        .Column("Id").AsInt32().Required()
        .Column("Name").AsString().Required())
    .ValidateOrThrow()
    .Map<Person>(map => map
        .FromColumn<int>("Id", (person, value) => { person.Id = value; return person; })
        .FromColumn<string>("Name", (person, value) => { person.Name = value; return person; }))
    .ToList();

public sealed class Person {
    public int Id { get; set; }
    public string Name { get; set; } = "";
}

Export Word to PDF

using OfficeIMO.Word;
using OfficeIMO.Word.Pdf;

using var document = WordDocument.Load("proposal.docx");
document.SaveAsPdf("proposal.pdf");

Read, split, merge, and stamp PDFs

using OfficeIMO.Pdf;

using var source = PdfDocument.Open("packet.pdf");

string firstPageText = source.Read.Text("1");
source.Pages.Extract("1-3").Save("packet-summary.pdf");

PdfDocument.Open("packet.pdf")
    .MergeWith("appendix.pdf")
    .Pages.Delete("2")
    .Stamp.Text("Reviewed")
    .Save("packet-final.pdf");

Convert PDF tables back into editable Office files

using OfficeIMO.Excel.Pdf;
using OfficeIMO.Word.Pdf;

PdfExcelTableConverterExtensions.SaveAsExcelFromPdfTables(
    "statement.pdf",
    "statement-tables.xlsx");

PdfWordTableConverterExtensions.SaveAsWordFromPdfTables(
    "statement.pdf",
    "statement-tables.docx");

Convert Markdown and HTML to PDF, PNG, and SVG

using OfficeIMO.Markdown.Pdf;

"# Status\n\nGenerated by OfficeIMO."
    .SaveAsPdfFromMarkdown("status.pdf");

using OfficeIMO.Html;
using OfficeIMO.Html.Pdf;

string html = "<h1>Status</h1><p>Generated by OfficeIMO.</p>";
var options = new HtmlPdfSaveOptions {
    Margins = HtmlRenderMargins.All(32)
};

byte[] pdf = html.ToPdf(options);
byte[] png = html.ToPng(options);
string svg = html.ToSvg(options);

var pdfResult = html.ToPdfDocumentResult(options);
var pngResult = html.ToPngResult(options);
var svgResult = html.ToSvgResult(options);

html.SaveAsPdf("status.pdf", options);
html.SaveAsPng("status.png", options);
html.SaveAsSvg("status.svg", options);

Extract content for indexing or RAG

using OfficeIMO.Reader;
using OfficeIMO.Reader.Pdf;
using OfficeIMO.Reader.Zip;

OfficeDocumentReader reader = new OfficeDocumentReaderBuilder()
    .AddPdfHandler()
    .AddZipHandler()
    .Build();

var chunks = reader.ReadFolder("KnowledgeBase",
    new ReaderFolderOptions {
        Recurse = true,
        MaxFiles = 500,
        DeterministicOrder = true
    },
    new ReaderOptions {
        MaxChars = 8_000,
        ComputeHashes = true
    }).ToList();

Create a Visio diagram

using OfficeIMO.Visio;
using OfficeIMO.Visio.Diagrams;

VisioDocument.Create("network.vsdx")
    .NetworkTopologyDiagram("Branch topology", topology => topology
        .Title()
        .Root("internet", "Internet", VisioNetworkNodeKind.Internet)
        .Firewall("firewall", "Firewall")
        .Switch("core", "Core Switch")
        .Server("app", "App Server")
        .Ethernet("internet", "firewall", "WAN")
        .Trunk("firewall", "core")
        .Trunk("core", "app"))
    .Save();

Target frameworks

Most shipping libraries target netstandard2.0, net8.0, and net10.0. Some packages also include net472 or Windows-specific targets where the surface requires it. Check the package README or project file for exact targets.

Deeper docs

• Breaking API migration

• Examples

• PDF current state

• Excel roadmap

• Markdown correctness roadmap

• Visio assessment

• Website notes

• Changelog