How to Redact Text and Regions in PDFs Using IronPDF and C#

What Does the Redacted PDF Look Like?

Result PDF from redacting the Alaric phrase from all pages.

Use RedactTextOnPage and RedactTextOnPages methods to redact text from a single or multiple pages, respectively.

What Parameters Control Text Redaction?

Here are the parameters of the redact text methods and their purposes:

• ReplaceText: This is the text string that you want to redact.
• CaseSensitive: A boolean value indicating whether the search should be case-sensitive. If true, it will match capital and lower-case letters exactly. The default is false.
• OnlyMatchWholeWords: A boolean value specifying whether to match only whole words. The default is true.
• DrawRectangles: A boolean value determining whether to draw black rectangles around the redacted areas. The default is true.
• ReplacementText: This is the text that will be written in place of the redacted items. The default replacement text is "*".

Here's a more comprehensive example showing how to use these parameters:

using IronPdf;

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

// Redact with custom parameters
pdf.RedactTextOnAllPages("SSN: 123-45-6789", 
    caseSensitive: true, 
    onlyMatchWholeWords: false, 
    drawRectangles: true, 
    replacementText: "[REDACTED]");

// Redact multiple sensitive items
string[] sensitiveTerms = { "salary", "password", "credit card" };
foreach (string term in sensitiveTerms)
{
    pdf.RedactTextOnAllPages(term, caseSensitive: false);
}

pdf.SaveAs("fully_redacted_report.pdf");

using IronPdf;

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

// Redact with custom parameters
pdf.RedactTextOnAllPages("SSN: 123-45-6789", 
    caseSensitive: true, 
    onlyMatchWholeWords: false, 
    drawRectangles: true, 
    replacementText: "[REDACTED]");

// Redact multiple sensitive items
string[] sensitiveTerms = { "salary", "password", "credit card" };
foreach (string term in sensitiveTerms)
{
    pdf.RedactTextOnAllPages(term, caseSensitive: false);
}

pdf.SaveAs("fully_redacted_report.pdf");

For handling documents with complex formatting, consider reviewing how to manage fonts to ensure proper text recognition during redaction.

Advanced Region Redaction Examples

When working with complex documents, you may need to redact multiple regions or calculate coordinates dynamically:

using IronPdf;
using IronSoftware.Drawing;
using System.Collections.Generic;

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

// Redact multiple regions
List<RectangleF> regionsToRedact = new List<RectangleF>
{
    new RectangleF(100, 200, 200, 50),  // Signature area
    new RectangleF(100, 300, 200, 100), // Address block
    new RectangleF(350, 150, 150, 150)  // Photo ID area
};

foreach (var region in regionsToRedact)
{
    pdf.RedactRegionsOnAllPages(region);
}

// Redact regions on specific pages only
pdf.RedactRegionOnPage(0, new RectangleF(50, 50, 100, 30)); // Page 1 header
pdf.RedactRegionOnPages(new[] { 2, 3, 4 }, new RectangleF(400, 700, 150, 50)); // Footer on pages 3-5

pdf.SaveAs("form_redacted.pdf");

using IronPdf;
using IronSoftware.Drawing;
using System.Collections.Generic;

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

// Redact multiple regions
List<RectangleF> regionsToRedact = new List<RectangleF>
{
    new RectangleF(100, 200, 200, 50),  // Signature area
    new RectangleF(100, 300, 200, 100), // Address block
    new RectangleF(350, 150, 150, 150)  // Photo ID area
};

foreach (var region in regionsToRedact)
{
    pdf.RedactRegionsOnAllPages(region);
}

// Redact regions on specific pages only
pdf.RedactRegionOnPage(0, new RectangleF(50, 50, 100, 30)); // Page 1 header
pdf.RedactRegionOnPages(new[] { 2, 3, 4 }, new RectangleF(400, 700, 150, 50)); // Footer on pages 3-5

pdf.SaveAs("form_redacted.pdf");

What Does Region Redaction Look Like?

The result PDF is from redacting a region on the coordinates (5,700) with a width and height of 50 pixels.

When Should I Use Region vs Text Redaction?

Use RedactRegionOnPage and RedactRegionOnPages methods to redact regions from a single or multiple pages, respectively.

Region redaction is ideal when:

• You need to remove images, logos, or graphical elements
• The sensitive content includes handwritten notes or signatures
• You're dealing with forms where the layout is fixed
• You want to redact entire sections regardless of text content

Text redaction is better when:

• You're searching for specific keywords or phrases
• The content to redact appears in multiple locations
• You need case-sensitive or whole-word matching
• The document structure may vary between files

For comprehensive PDF security, combine redaction with other security features. Learn more about signing PDFs and explore PDF compression to optimize your secured documents.

Best Practices for PDF Redaction

When implementing redaction in your applications:

1. Always save to a new file: Never overwrite the original document to maintain an audit trail
2. Verify redaction completeness: Review the output to ensure all sensitive data is removed
3. Consider metadata: Remember to also edit and remove metadata that might contain sensitive information
4. Test coordinate calculations: When using region redaction, test your coordinate calculations across different page sizes and orientations

For additional document processing needs, explore how to extract text and images from PDFs before applying redaction, or learn about creating PDF forms with built-in privacy controls.

Ready to see what else you can do? Check out our tutorial page here: Edit PDFs