Message icon
Skip to footer content
Features
SIGN & SECURE

Sign and Secure PDFs

Secure and guarantee PDF authenticity with modern encryption, permissions, and signatures in a few lines of code.

IRONPDFFEATURES

Ensure Your Document Authenticity
Enhance with Seamless PDF Form Management
Assure the Safety of Your Documentation

Icon Main related to Sign and Secure PDFs
Ensure Your Document Authenticity

1

Digital Signature

Digitally sign your PDFs to authenticate them and provide proof of authorship or approval. This feature is essential for legal or official documentation.

Learn how to:sign your PDFs 
using IronPdf;
using IronPdf.Signing;
// Cryptographically sign an existing PDF in 1 line of code!
new IronPdf.Signing.PdfSignature("Iron.p12", "123456").SignPdfFile("any.pdf");
C#
2

Edit & Sign Revision History

Maintain and edit the revision history of your PDF documents. Track changes, approvals, and signatures over time for better document management.

Learn how to:edit and revision PDFs 
using IronPdf;
using IronPdf.Rendering;
// Import PDF and enable TrackChanges
PdfDocument pdf = PdfDocument.FromFile("annual_census.pdf", TrackChanges: ChangeTrackingModes.EnableChangeTracking);
// ... Various edits ...
pdf.SignWithFile("/assets/IronSignature.p12", "password", null, IronPdf.Signing.SignaturePermissions.AdditionalSignaturesAndFormFillingAllowed);
PdfDocument pdfWithRevision = pdf.SaveAsRevision();
pdfWithRevision.SaveAs("annual_census_2.pdf");
C#
3

Edit PDF Metadata

Edit the metadata of your PDF files, such as author, title, and subject, to improve document organization and searchability.

Learn how to:edit Metadata 
using IronPdf;
using System;

ChromePdfRenderer renderer = new ChromePdfRenderer();
PdfDocument pdf = renderer.RenderHtmlAsPdf("<h1>Metadata</h1>");
// Access the MetaData class and set the pre-defined metadata properties.
pdf.MetaData.Author = "Iron Software";
pdf.MetaData.CreationDate = DateTime.Today;
pdf.MetaData.Creator = "IronPDF";
pdf.SaveAs("pdf-with-metadata.pdf");
C#

Icon Main related to Sign and Secure PDFs
Enhance with Seamless PDF Form Management

1

Create PDF Forms

Create interactive PDF forms with fillable fields, checkboxes, radio buttons, and more. Ideal for gathering information or creating surveys.

Learn how to:create PDF forms 
using IronPdf;

// Input and Text Area forms HTML
string FormHtml = @"
<html>
    <body>
        <h2>Editable PDF Form</h2>
        <form>
            First name: <br> <input type='text' name='firstname' value=''> <br>
            Last name: <br> <input type='text' name='lastname' value=''> <br>
            Address: <br> <textarea name='address' rows='4' cols='50'></textarea>
        </form>
    </body>
</html>
";

// Instantiate Renderer
ChromePdfRenderer Renderer = new ChromePdfRenderer();
Renderer.RenderingOptions.CreatePdfFormsFromHtml = true;
Renderer.RenderHtmlAsPdf(FormHtml).SaveAs("textAreaAndInputForm.pdf");
C#
2

Fill & Edit Existing Forms

Fill out and edit existing PDF forms with ease. Modify form fields, update content, and save changes for seamless document management.

Learn how to:fill and edit forms 
using IronPdf;

PdfDocument pdf = PdfDocument.FromFile("textAreaAndInputForm.pdf");

// Set text input form values
pdf.Form.FindFormField("firstname").Value = "John";
pdf.Form.FindFormField("lastname").Value = "Smith";

// Set text area form values
pdf.Form.FindFormField("address").Value = "Iron Software LLC\r\n205 N. Michigan Ave.";

pdf.SaveAs("textAreaAndInputFormEdited.pdf");
C#
3

Flatten Form Fields

Flatten form fields to lock in entered data and prevent further edits, ensuring the integrity of the form content.

Learn how to:flatten form fields 
using IronPdf;

// Select the desired PDF File
PdfDocument pdf = PdfDocument.FromFile("textAreaAndInputFormEdited.pdf");

// Flatten the pdf
pdf.Flatten();

// Save as a new file
pdf.SaveAs("after_flatten.pdf");
C#

Icon Main related to Sign and Secure PDFs
Assure the Safety of Your Documentation

1

Sanitize PDFs

Sanitize your PDFs by removing hidden metadata, sensitive content, and comments to protect your document's confidentiality and security.

Learn how to:sanitize PDFs 
using IronPdf;

// Import PDF document
PdfDocument pdf = PdfDocument.FromFile("sample.pdf");

// Sanitize with Bitmap
PdfDocument sanitizeWithBitmap = Cleaner.SanitizeWithBitmap(pdf);

// Sanitize with SVG
PdfDocument sanitizeWithSvg = Cleaner.SanitizeWithSvg(pdf);

// Export PDFs
sanitizeWithBitmap.SaveAs("sanitizeWithBitmap.pdf");
sanitizeWithSvg.SaveAs("sanitizeWithSvg.pdf");
C#
2

Set Password & Permissions

Set passwords and permissions on your PDFs to control access, prevent unauthorized editing, and protect sensitive information.

Learn how to:set PDFs permissions 
using IronPdf;

ChromePdfRenderer renderer = new ChromePdfRenderer();

PdfDocument pdf = renderer.RenderHtmlAsPdf("<h1>Secret Information:</h1> Hello World");

// Password to edit the pdf
pdf.SecuritySettings.OwnerPassword = "123password";

// Password to open the pdf
pdf.SecuritySettings.UserPassword = "password123";
pdf.SaveAs("protected.pdf");
C#
Ready to Get Started?
Nuget Downloads 16,383,823 | Version: 2025.11 just released
30-day trial → Full product. No limits. No card. Start Free Trial