Document SDK .NET Word Library Digital Signature In Word Document

Secure Word documents with certificate-based digital signatures using the Syncfusion .NET Word Library. Add visible or invisible signatures, validate authenticity, and manage signature lines without Microsoft Word or Office Interop.

Create signature lines with signer details & images
Validate, manage, and remove digital signatures without Word or Office Interop

FREE TRIAL

No credit card required.

VIEW DEMO

No credit card required.

Enterprise digital signature workflows

Implement complete Word document digital signature workflows with certificate-based signing, integrity validation, compliance support, and enterprise approval processes.

Office-free signing

Digitally sign and validate Word documents without Microsoft Word using X.509 (.pfx) certificates. Create visible or invisible signatures, including signature lines, signer details, and optional signature images.

Multi-signer validation

Enable multi-party approval workflows with multiple signature lines and unique IDs. Validate document integrity through signature status, signing time, comments, and signature collections across .NET applications.

Enterprise signature standards

Configure advanced digital signature standards using SignatureSettings.XmlDsigLevel to generate XmlDSig or XAdES-EPES compliant signatures. Ensure authenticity, integrity, and long-term trust.

Add an invisible digital signature

Apply a certificate-based digital signature that protects the complete Word document without adding a visible signature object. Configure the signing time and optional comments through SignatureSettings.

Add invisible digital signatures to DOCX files using X.509 certificates.
Protect document content from unauthorized modifications.
Configure signing time, comments, and signature settings programmatically.
Preserve document appearance while ensuring authenticity.

Invisible signature.

Visible Signature.

Add a visible digital signature

Create a visible signature line with the signer name, title, email, and date visibility, then sign it using its unique signature line ID, an X.509 certificate, and an optional signature image. You can also create and sign multiple signature lines independently to support multi-party and staged approval workflows.

Create signature lines with signer details, title, email, and date information.
Sign signature lines using X.509 certificates and signature images.
Support multiple independent signatures in a single document.
Enable multi-party and sequential approval workflows.

Validate digital signatures

Detect signed documents, inspect signature count, validity, comments, and signing time, and validate all signatures as a collection.

Detect whether a Word document contains digital signatures.
Validate signature authenticity and document integrity.
Retrieve signature details such as comments and signing time.
Validate multiple digital signatures in a single operation.

Validate Signature.

Remove signature.

Remove digital signatures

Remove all digital signatures when a document needs revision, then save an unsigned copy for a new signing cycle.

Remove all digital signatures programmatically from DOCX files.
Prepare signed documents for editing and revision cycles.
Save unsigned copies for re-signing workflows.
Simplify document version management and approvals.

Sign using XmlDSig standard

Apply W3C-compliant XML Digital Signatures to Word documents by setting SignatureSettings.XmlDsigLevel to XmlDsigLevel.XmlDSig. This standard helps ensure secure, interoperable, and verifiable document signing workflows.

Create standards-compliant XMLDSig signatures in DOCX files.
Improve interoperability across digital signature systems.
Configure XMLDSig support through signature settings.
Ensure document integrity with standardized signature validation.

Sign with XmlDSig standard.

Sign with XAdES-EPES standard

Sign using XAdES-EPES standard

Generate advanced electronic signatures that comply with XAdES-EPES requirements for enhanced trust and policy-based signing.

Create policy-aware XAdES-EPES digital signatures.
Support advanced electronic signature workflows.
Strengthen compliance with digital signing requirements.
Apply signature policies through configurable settings.

See Why Developers Love Syncfusion

Our Customers Love Us

Having an excellent set of tools and a great support team, Syncfusion reduces customers’ development time. Here are some of their experiences.

Ibrahim M,

Contractor and CEO

What a Deal….Syncfusion Essential Studio.

With very few lines of code I can generate Excel, Word or PDFs. I can customize the look and feel of the CRUD presentation easily. I am looking forward to trying out the other control suites that Syncfusion provides.

Jaish Mathews,

Chief Applications Architect

Syncfusion Essential Studio Review

We use Syncfusion Essential Studio for RAD purpose. It has been used for Blazor and .NET Core Razor UI implementations. It really saved time on Web UI development. Additionally PDF & EXCEL components saved time in back-end development as well.

Frequently Asked Questions

What is a digital signature in a Word document?

A digital signature is a certificate-based signature that authenticates the signer and helps verify that document content has not been altered after signing.

How is the signature image attached?

Set SignatureSettings.SignatureImage to the image byte array and set SignatureLineId to the ID of the target signature line before calling AddDigitalSignature.

Can documents be signed on a server without Word?

Yes. The Syncfusion .NET Word Library is a managed library and does not require Microsoft Word or Office Interop.

Which class loads the certificate used for signing?

Use OfficeDigitalSignatureCertificate with the path to a .pfx file and its password, then pass the certificate to AddDigitalSignature together with SignatureSettings.

How are all signatures validated at once?

Use document.DigitalSignatures.IsValid. To inspect signatures individually, iterate through document.DigitalSignatures and review IsValid, Comments, and SigningTime.