Frequently Asked Questions

Licensing & Open Source

What is the licensing model for Aspose.Words FOSS for .NET?

Aspose.Words FOSS for .NET is released under the MIT License. You may use it in personal, commercial, and closed-source projects free of charge, with no royalty and no runtime license key or activation step — you only need to keep the copyright notice and license text with any copy of the software you distribute.

How does this FOSS edition differ from the commercial Aspose.Words for .NET product?

Aspose.Words FOSS for .NET is not a rewrite or a wrapper — it is the actual Aspose.Words for .NET source code, reduced to a free, open-source core. It exposes the same Document Object Model as the commercial product (Document, DocumentBuilder, Section, Paragraph, Run, Table, and related classes), but leaves out the page-layout and rendering subsystem, several legacy and open-document formats, mail merge execution, LINQ Reporting, document comparison, and embedded-font subsetting. Digital signatures can be verified but not created. See the format and limitations questions below for the specifics. Developers who need the full feature set can use Aspose.Words for .NET alongside these open-source resources.

Installation & Requirements

How do I install Aspose.Words FOSS for .NET?

A NuGet package has not been published yet, so the library must be built from source. Clone the repository and build the solution in Release configuration, then add a project reference to Aspose.Words.csproj from your own application:

git clone https://github.com/aspose-words-foss/Aspose.Words-FOSS-for-.NET.git
cd Aspose.Words-FOSS-for-.NET
dotnet build Aspose.Words.sln -c Release

What .NET versions and operating systems are supported?

The library targets .NET Standard 2.0, so it runs on .NET Framework 4.6.2+ and .NET 6/8/10, on Windows, Linux, and macOS. It is pure managed C# with no native dependencies, so no additional system packages need to be installed.

Format Support

Which file formats can Aspose.Words FOSS for .NET read and write?

Format	Load	Save
DOCX	Yes	Yes
DOCM	Yes	Yes
DOTX	Yes	Yes
DOTM	Yes	Yes
Flat OPC (plus macro-enabled and template variants)	Yes	Yes
Markdown	Yes	Yes
Plain text	Yes	Yes

DOCX, DOCM, DOTX, DOTM, and Flat OPC all share the same OOXML reader/writer.

Can I load or save DOC, RTF, ODT, HTML, or EPUB files?

No. This edition’s format list stops at DOCX, DOCM, DOTX, DOTM, Flat OPC, Markdown, and plain text — .doc, .rtf, .odt, .html, and .epub sit outside that list, and opening any such file raises an exception.

Can Aspose.Words FOSS for .NET export documents to PDF, XPS, or image formats?

No. This edition does not include the page-layout and rendering subsystem, so Document.Save() cannot export to PDF, XPS, or image formats.

Save to DOCX, DOCM, DOTX, DOTM, Flat OPC, Markdown, or plain text instead. The commercial Aspose.Words for .NET adds PDF, XPS, and image formats.

API Usage

How do I create a new document?

Construct a Document, wrap it in a DocumentBuilder, and use the builder’s high-level methods to insert content before saving:

using Aspose.Words;

Document doc = new Document();
DocumentBuilder builder = new DocumentBuilder(doc);

builder.Writeln("Hello, Aspose.Words FOSS!");

doc.Save("output.docx");

How do I load an existing DOCX document?

Pass the file path to the Document constructor: new Document("input.docx"). The same constructor also accepts a Stream, and both have overloads that take a LoadOptions object for finer control over how the file is parsed.

How do fields such as DATE or DOCPROPERTY get updated?

Aspose.Words FOSS for .NET includes a full field evaluation engine, so content fields like DATE, DOCPROPERTY, REF, SEQ, and mail-merge fields update programmatically. Fields that depend on page layout — such as page numbers in a table of contents — evaluate to a placeholder 0 instead of a computed value, because this edition does not include the layout engine that would normally paginate the document.

Known Limitations

Does this edition support executing mail merges, LINQ Reporting, or comparing documents?

No. Mail merge execution, LINQ Reporting, document comparison, and embedded-font subsetting are not included in this FOSS edition. The classes that model mail-merge settings and fields (for example MailMergeSettings) are present in the object model, but running an actual merge is not part of this edition.

Can Aspose.Words FOSS for .NET create a digital signature on a document?

No. This edition can inspect and verify digital signatures already attached to a .docx file — through Document.DigitalSignatures, DigitalSignatureUtil.LoadSignatures(), and the DigitalSignature/DigitalSignatureCollection classes — but it cannot create new signatures. A signing workflow requires the commercial Aspose.Words for .NET.

Is embedded-font subsetting supported?

No. When EmbedTrueTypeFonts is enabled, fonts are embedded as whole files rather than being subsetted to only the glyphs actually used in the document.