How to Redact Regions in PDF Files with C#

Curtis Chau

Updated: August 2, 2026

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  # How to Redact Regions in PDF Files with C&num; Redacting sensitive information in PDF documents is crucial for ensuring privacy and compliance with data protection regulations. The [POST] Redact Region API from IronSecure Doc offers an efficient way to hide sensitive text and information in specific regions of a PDF document using true redaction. This API ensures that the redacted data is completely removed and cannot be recovered, making it ideal for handling confidential information in legal, financial, or personal documents. <div class="hsg-featured-snippet"> <h2>How to Redact Regions in PDF Files</h2> <ol> <li><a class="js-modal-open" data-modal-id="trial-license-after-download" href="https://hub.docker.com/r/ironsoftwareofficial/ironsecuredoc">Pull and start the IronSecureDoc Docker Image</a></li> <li>Try out the API using Swagger</li> <li>Set up the arguments</li> <li>Call the API from any preferred language</li> <li>Download the resulting PDF document</li> </ol> </div> ## Pull and Start IronSecureDoc If you don't have IronSecureDoc running yet, please follow the links below to get it set up: <table class="table"> <tr style="background-color: rgb(241 249 251);"> <th style="text-align: center;">Host Locally</th> <th style="text-align: center;">Deploy to Cloud</th> </tr> <tr> <td style="vertical-align: top;"> <ul> <li><a href="/enterprise/securedoc/tutorials/hosting-windows/">Hosting on Windows</a></li> <li><a href="/enterprise/securedoc/tutorials/hosting-mac/">Hosting on Mac</a></li> <li><a href="/enterprise/securedoc/tutorials/hosting-linux/">Hosting on Linux</a></li> </ul> </td> <td style="vertical-align: top;"> <ul> <li><a href="/enterprise/securedoc/tutorials/set-up-azure/">Deploy on Azure Container</a></li> <li><a href="/enterprise/securedoc/tutorials/set-up-aws/">Deploy on AWS Container</a></li> </ul> </td> </tr> </table> ## The [POST] Redact Region API The [POST] Redact Region API endpoint allows you to hide sensitive information within specific regions of a PDF document using true redaction. This feature is crucial for applications that manage confidential documents, such as legal contracts, medical records, or financial statements. By leveraging this API, you can ensure that sensitive text within defined areas of a PDF is permanently removed, offering both security and compliance. [[i:(Once a region is redacted, the content within that area cannot be recovered.)]] ## Trying It Out in Swagger Swagger is a powerful tool that enables developers to interact with RESTful APIs through a user-friendly web interface. Whether you're using languages like Python, Java, or others, Swagger offers a convenient way to test and implement this API. ### Steps to Redact Region with Swagger 1. **Access the Swagger UI:** If your API server is running locally, you can access Swagger by navigating to `http://localhost:8080/swagger/index.html` in your web browser.  2. **Locate the [POST] `/v1/document-services/pdfs/redact-region` endpoint:** Within the Swagger UI, find the `POST /v1/document-services/pdfs/redact-region` endpoint.  3. **Specify Redaction Coordinates:** In this example, we will remove a table from the PDF on page index 1 (i.e., Page #2). Use the following coordinates to define the redaction region: - Page index (`specific_pages`): 1 - X Coordinate (`region_to_redact_x`): 60 - Y Coordinate (`region_to_redact_y`): 270 - Width (`region_to_redact_w`): 470 - Height (`region_to_redact_h`): 200 4. **Set Optional Parameters:** Optionally, you can add a user or owner password, specify specific pages, or decide whether to draw a black box over the redacted area and save the document with PDF/A or PDF/UA compliance.  5. **Upload a Sample PDF:** In the request body, upload a sample PDF file where you want to apply the redaction. Ensure that the file is added as **`pdf_file`**. 6. **Execute the Request:** Click "Execute" to run the request. The response will include the redacted PDF, with the table removed from page index 1 as specified.  This Swagger UI interaction allows you to easily test the redaction process, providing immediate feedback on how the coordinates affect the PDF content. 7. **Check the Output PDF:** The redacted region will be on page 2. <iframe src="/static-assets/securedoc/how-to/redact-region/output.pdf#page=2" width="100%" height="400px"> This browser does not support PDFs. Please download the PDF to view it: <a href="/static-assets/securedoc/how-to/redact-region/output.pdf">Download PDF</a>. </iframe> <hr /> ## Understanding Input Parameters Before using this API, it's essential to understand the input parameters required and optional for redacting a region in your PDF. These parameters help define the specific area to redact. ### Key Parameters - **`pdf_file`:** The PDF document you want to redact. - **`region_to_redact_x`:** X coordinate of the region to redact (starting from the bottom-left of the page). - **`region_to_redact_y`:** Y coordinate of the region to redact (starting from the bottom-left of the page). - **`region_to_redact_w`:** Width of the region to redact. - **`region_to_redact_h`:** Height of the region to redact. ### Optional Parameters - **`user_password`:** If the PDF is password-protected, provide the user password. - **`owner_password`:** Provide the owner password if modifications are restricted. - **`specific_pages`:** Specify which pages to redact. If not provided, the redaction applies to all pages. - **`save_as_pdfa`:** Save the PDF with PDF/A-3 compliance. - **`save_as_pdfua`:** Save the PDF with PDF/UA compliance. <hr /> ## API Integration: Python Example Once you're familiar with the parameters, you can call this API using your preferred programming language. Below is an example of how to integrate this API using Python. ```python import requests # Define the API endpoint URL url = 'http://localhost:8080/v1/document-services/pdfs/redact-region' # Set the headers for the request (optional relevant metadata) headers = { 'accept': '*/*', 'author': 'Iron Software', 'title': 'REDACT REGION DEMO 2024', 'subject': 'DEMO EXAMPLE' } # Open the PDF file to be redacted in binary read mode files = { 'pdf_file': ('sample_file.pdf', open('sample_file.pdf', 'rb'), 'application/pdf') } # Define the coordinates and page for the redaction region data = { 'region_to_redact_x': '60', # X-coordinate starting at the bottom-left 'region_to_redact_y': '270', # Y-coordinate starting at the bottom-left 'region_to_redact_w': '470', # Width of the region to be redacted 'region_to_redact_h': '200', # Height of the region to be redacted 'specific_pages': [1] # Specify the page index to redact } # Make the POST request to the API with the provided parameters and file response = requests.post(url, headers=headers, files=files, data=data) # Save the redacted PDF response to a new file with open('redacted_output.pdf', 'wb') as f: f.write(response.content) print('PDF redacted successfully.') ``` This code performs the following steps: - **Load the PDF:** The PDF file to be redacted is loaded from the local file system. - **Set Redaction Parameters:** Specify the coordinates (X, Y), width, height, and specific page to redact. - **Call the API:** The [POST] Redact Region API is called, passing in the necessary parameters. - **Save the Result:** The redacted PDF is saved as a new file. The given region is redacted as shown below. 

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Redacting sensitive information in PDF documents is crucial for ensuring privacy and compliance with data protection regulations. The [POST] Redact Region API from IronSecure Doc offers an efficient way to hide sensitive text and information in specific regions of a PDF document using true redaction. This API ensures that the redacted data is completely removed and cannot be recovered, making it ideal for handling confidential information in legal, financial, or personal documents.

Pull and Start IronSecureDoc

If you don't have IronSecureDoc running yet, please follow the links below to get it set up:

The [POST] Redact Region API

The [POST] Redact Region API endpoint allows you to hide sensitive information within specific regions of a PDF document using true redaction. This feature is crucial for applications that manage confidential documents, such as legal contracts, medical records, or financial statements. By leveraging this API, you can ensure that sensitive text within defined areas of a PDF is permanently removed, offering both security and compliance.

Trying It Out in Swagger

Swagger is a powerful tool that enables developers to interact with RESTful APIs through a user-friendly web interface. Whether you're using languages like Python, Java, or others, Swagger offers a convenient way to test and implement this API.

Steps to Redact Region with Swagger

1. Access the Swagger UI:

   If your API server is running locally, you can access Swagger by navigating to http://localhost:8080/swagger/index.html in your web browser.

   

2. Locate the [POST] /v1/document-services/pdfs/redact-region endpoint:

   Within the Swagger UI, find the POST /v1/document-services/pdfs/redact-region endpoint.

   

3. Specify Redaction Coordinates:

   In this example, we will remove a table from the PDF on page index 1 (i.e., Page #2). Use the following coordinates to define the redaction region:

   • Page index (specific_pages): 1
   • X Coordinate (region_to_redact_x): 60
   • Y Coordinate (region_to_redact_y): 270
   • Width (region_to_redact_w): 470
   • Height (region_to_redact_h): 200

4. Set Optional Parameters:

   Optionally, you can add a user or owner password, specify specific pages, or decide whether to draw a black box over the redacted area and save the document with PDF/A or PDF/UA compliance.

   

5. Upload a Sample PDF:

   In the request body, upload a sample PDF file where you want to apply the redaction. Ensure that the file is added as pdf_file.

6. Execute the Request:

   Click "Execute" to run the request. The response will include the redacted PDF, with the table removed from page index 1 as specified.

   

   This Swagger UI interaction allows you to easily test the redaction process, providing immediate feedback on how the coordinates affect the PDF content.

7. Check the Output PDF:

   The redacted region will be on page 2.

Understanding Input Parameters

Before using this API, it's essential to understand the input parameters required and optional for redacting a region in your PDF. These parameters help define the specific area to redact.

Key Parameters

• pdf_file: The PDF document you want to redact.
• region_to_redact_x: X coordinate of the region to redact (starting from the bottom-left of the page).
• region_to_redact_y: Y coordinate of the region to redact (starting from the bottom-left of the page).
• region_to_redact_w: Width of the region to redact.
• region_to_redact_h: Height of the region to redact.

Optional Parameters

• user_password: If the PDF is password-protected, provide the user password.
• owner_password: Provide the owner password if modifications are restricted.
• specific_pages: Specify which pages to redact. If not provided, the redaction applies to all pages.
• save_as_pdfa: Save the PDF with PDF/A-3 compliance.
• save_as_pdfua: Save the PDF with PDF/UA compliance.

API Integration: Python Example

Once you're familiar with the parameters, you can call this API using your preferred programming language. Below is an example of how to integrate this API using Python.

import requests

# Define the API endpoint URL
url = 'http://localhost:8080/v1/document-services/pdfs/redact-region'

# Set the headers for the request (optional relevant metadata)
headers = {
    'accept': '*/*',
    'author': 'Iron Software',
    'title': 'REDACT REGION DEMO 2024',
    'subject': 'DEMO EXAMPLE'
}

# Open the PDF file to be redacted in binary read mode
files = {
    'pdf_file': ('sample_file.pdf', open('sample_file.pdf', 'rb'), 'application/pdf')
}

# Define the coordinates and page for the redaction region
data = {
    'region_to_redact_x': '60',  # X-coordinate starting at the bottom-left
    'region_to_redact_y': '270', # Y-coordinate starting at the bottom-left
    'region_to_redact_w': '470', # Width of the region to be redacted
    'region_to_redact_h': '200', # Height of the region to be redacted
    'specific_pages': [1]        # Specify the page index to redact
}

# Make the POST request to the API with the provided parameters and file
response = requests.post(url, headers=headers, files=files, data=data)

# Save the redacted PDF response to a new file
with open('redacted_output.pdf', 'wb') as f:
    f.write(response.content)

print('PDF redacted successfully.')

import requests

# Define the API endpoint URL
url = 'http://localhost:8080/v1/document-services/pdfs/redact-region'

# Set the headers for the request (optional relevant metadata)
headers = {
    'accept': '*/*',
    'author': 'Iron Software',
    'title': 'REDACT REGION DEMO 2024',
    'subject': 'DEMO EXAMPLE'
}

# Open the PDF file to be redacted in binary read mode
files = {
    'pdf_file': ('sample_file.pdf', open('sample_file.pdf', 'rb'), 'application/pdf')
}

# Define the coordinates and page for the redaction region
data = {
    'region_to_redact_x': '60',  # X-coordinate starting at the bottom-left
    'region_to_redact_y': '270', # Y-coordinate starting at the bottom-left
    'region_to_redact_w': '470', # Width of the region to be redacted
    'region_to_redact_h': '200', # Height of the region to be redacted
    'specific_pages': [1]        # Specify the page index to redact
}

# Make the POST request to the API with the provided parameters and file
response = requests.post(url, headers=headers, files=files, data=data)

# Save the redacted PDF response to a new file
with open('redacted_output.pdf', 'wb') as f:
    f.write(response.content)

print('PDF redacted successfully.')

This code performs the following steps:

• Load the PDF: The PDF file to be redacted is loaded from the local file system.
• Set Redaction Parameters: Specify the coordinates (X, Y), width, height, and specific page to redact.
• Call the API: The [POST] Redact Region API is called, passing in the necessary parameters.
• Save the Result: The redacted PDF is saved as a new file.

The given region is redacted as shown below.

Curtis Chau

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Technical Writer

Curtis Chau holds a Bachelor’s degree in Computer Science (Carleton University) and specializes in front-end development with expertise in Node.js, TypeScript, JavaScript, and React. Passionate about crafting intuitive and aesthetically pleasing user interfaces, Curtis enjoys working with modern frameworks and creating well-structured, visually appealing manuals.

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