using IronPdf; // Disable local disk access or cross-origin requests Installation.EnableWebSecurity = true; // Instantiate Renderer var renderer = new ChromePdfRenderer(); // Create a PDF from a HTML string using C# var pdf = renderer.RenderHtmlAsPdf("<h1>Hello World</h1>"); // Export to a file or Stream pdf.SaveAs("output.pdf"); // Advanced Example with HTML Assets // Load external html assets: Images, CSS and JavaScript. // An optional BasePath 'C:\site\assets\' is set as the file location to load assets from var myAdvancedPdf = renderer.RenderHtmlAsPdf("<img src='icons/iron.png'>", @"C:\site\assets\"); myAdvancedPdf.SaveAs("html-with-assets.pdf");

USING IRONPDF

Generating Fillable PDF Forms from HTML in C#

Curtis Chau

Updated:June 24, 2026

Intake forms, applications, surveys, and onboarding paperwork all share a pattern: a recipient needs to fill in fields and return the document. A static PDF cannot do that, and printing, scanning, and re-keying wastes everyone's time. IronPDF generates fillable PDF forms in C#, either from HTML markup the team already has or by placing fields programmatically onto an existing document.

The Business Problem

A healthcare provider needs patient intake forms, an insurer needs applications, an HR team needs onboarding documents. Each should arrive as a PDF the recipient can complete on screen, ideally with known details already filled in. Building these by hand in a PDF editor does not scale, and maintaining a separate form layout duplicates the web version that often already exists.

Generating a Form from HTML

Enabling one rendering option turns standard HTML form elements into interactive PDF fields, so existing markup becomes a fillable document.

using IronPdf;

string formHtml = @"
<html><body>
  <h2>Patient Intake</h2>
  <form>
    First name: <input type='text' name='firstname' value=''><br>
    Address: <textarea name='address' rows='4' cols='50'></textarea><br>
    Completed: <input type='checkbox' name='completed'><br>
    Priority:
    <select name='priority'>
      <option value='high'>High</option>
      <option value='low'>Low</option>
    </select>
  </form>
</body></html>";

var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.CreatePdfFormsFromHtml = true;
renderer.RenderHtmlAsPdf(formHtml).SaveAs("intake-form.pdf");

using IronPdf;

string formHtml = @"
<html><body>
  <h2>Patient Intake</h2>
  <form>
    First name: <input type='text' name='firstname' value=''><br>
    Address: <textarea name='address' rows='4' cols='50'></textarea><br>
    Completed: <input type='checkbox' name='completed'><br>
    Priority:
    <select name='priority'>
      <option value='high'>High</option>
      <option value='low'>Low</option>
    </select>
  </form>
</body></html>";

var renderer = new ChromePdfRenderer();
renderer.RenderingOptions.CreatePdfFormsFromHtml = true;
renderer.RenderHtmlAsPdf(formHtml).SaveAs("intake-form.pdf");

Imports IronPdf

Dim formHtml As String = "
<html><body>
  <h2>Patient Intake</h2>
  <form>
    First name: <input type='text' name='firstname' value=''><br>
    Address: <textarea name='address' rows='4' cols='50'></textarea><br>
    Completed: <input type='checkbox' name='completed'><br>
    Priority:
    <select name='priority'>
      <option value='high'>High</option>
      <option value='low'>Low</option>
    </select>
  </form>
</body></html>"

Dim renderer As New ChromePdfRenderer()
renderer.RenderingOptions.CreatePdfFormsFromHtml = True
renderer.RenderHtmlAsPdf(formHtml).SaveAs("intake-form.pdf")

$vbLabelText $csharpLabel

Because each field has a name and a value, the same approach pre-fills a form from a database, so a renewal notice or application arrives with the recipient's details already populated and only the gaps left to complete.

Adding Fields to an Existing Document

When the base document did not come from HTML, such as a scanned form or a generated report needing an approval field, fields can be placed programmatically at exact coordinates.

using IronSoftware.Forms;

PdfDocument pdf = renderer.RenderHtmlAsPdf("<h2>Approval</h2>");

var textForm = new TextFormField("approver", "", pageIndex: 0, x: 100, y: 700, width: 150, height: 15);
pdf.Form.Add(textForm);

pdf.SaveAs("approval-form.pdf");

using IronSoftware.Forms;

PdfDocument pdf = renderer.RenderHtmlAsPdf("<h2>Approval</h2>");

var textForm = new TextFormField("approver", "", pageIndex: 0, x: 100, y: 700, width: 150, height: 15);
pdf.Form.Add(textForm);

pdf.SaveAs("approval-form.pdf");

Imports IronSoftware.Forms

Dim pdf As PdfDocument = renderer.RenderHtmlAsPdf("<h2>Approval</h2>")

Dim textForm As New TextFormField("approver", "", pageIndex:=0, x:=100, y:=700, width:=150, height:=15)
pdf.Form.Add(textForm)

pdf.SaveAs("approval-form.pdf")

$vbLabelText $csharpLabel

Points to Plan For

Enable the form flag: Without CreatePdfFormsFromHtml set to true, HTML form elements render as static visuals rather than fillable fields. This is the most common reason a form is not editable.
Programmatic fields are coordinate-based: Fields added through code use absolute x, y, width, height, and a page index, which is precise but makes layout your responsibility.
Checkbox values: A checkbox uses "yes" and "no" rather than a boolean for its checked state.
Creating is not securing: Generating a form does not lock or sign it. Apply passwords, permissions, or signatures separately when the document needs protection.

Result

With one option for HTML forms and coordinate-based fields for everything else, teams ship fillable, pre-fillable documents that recipients complete on screen, with no manual form building. Full field types and options are in the create PDF forms guide.

Curtis Chau

Chat with engineering team now

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.

...

Updated June 24, 2026

Capturing WebGL Maps and 3D Visualizations as PDFs in C#

Capture GPU-accelerated WebGL maps, 3D dashboards, and model viewers as static PDFs in C# with IronPDF using single-process and hardware GPU mode.

Updated June 24, 2026

Adding Chat and Summary Features to Document-Heavy .NET Apps

Add AI summaries and chat-with-your-document querying to .NET apps with IronPDF, Semantic Kernel, and Azure OpenAI to triage dense PDFs fast.

Updated June 24, 2026

Self-Contained PDF Generation for Cloud and Serverless Apps

Embed images as base64 data URIs in C# with IronPDF to generate self-contained PDFs that render reliably in cloud, serverless, and archived environments.

Self-Contained PDF Generation for Cloud and Serverless Apps

Export MAUI Pages to PDF in .NET wi...