How to fill form & sign a PDF file in C#, VB.NET?
Syncfusion Essential PDF is a .NET PDF library used to create, read, and edit PDF documents. Using this library, you can fill all necessary form fields and sign a PDF file with PFX file (X509 Certificate) to maintain the authenticity and integrity.
Steps to fill form fields and sign a PDF file programmatically:
- Create a new C# console application project.
- Install the Syncfusion.Pdf.WinForms NuGet package as reference to your .NET Framework application from NuGet.org.
- Include the following namespace in the Program.cs file.
C#
using Syncfusion.Pdf; using Syncfusion.Pdf.Graphics; using Syncfusion.Pdf.Parsing; using Syncfusion.Pdf.Security; using System.Drawing;
VB.NET
Imports Syncfusion.Pdf Imports Syncfusion.Pdf.Graphics Imports Syncfusion.Pdf.Parsing Imports Syncfusion.Pdf.Security Imports System.Drawing
- Use the following code snippet to fill form and sign the PDF document.
C#
//Load the PDF document
PdfLoadedDocument loadedDocument = new PdfLoadedDocument("FormTemplate.pdf");
//Gets the first page of the document
PdfLoadedPage page = loadedDocument.Pages[0] as PdfLoadedPage;
//Get the loaded form
PdfLoadedForm form = loadedDocument.Form;
//Fill the fields from the first page
(form.Fields["Name"] as PdfLoadedTextBoxField).Text = "Simons";
(form.Fields["Email address"] as PdfLoadedTextBoxField).Text = "simonsbistro@outlook.com";
(form.Fields["Phone"] as PdfLoadedTextBoxField).Text = "31 12 34 56";
(form.Fields["Gender"] as PdfLoadedRadioButtonListField).SelectedIndex = 0;
(form.Fields["JobTitle"] as PdfLoadedComboBoxField).SelectedIndex = 1;
(form.Fields["Languages"] as PdfLoadedListBoxField).SelectedIndex = new int[1] { 2 };
(form.Fields["Associate degree"] as PdfLoadedCheckBoxField).Items[0].Checked = true;
//Sign a PDF file
PdfLoadedSignatureField signatureField = loadedDocument.Form.Fields[9] as PdfLoadedSignatureField;
PdfCertificate certificate = new PdfCertificate(@"PDF.pfx", "syncfusion");
signatureField.Signature = new PdfSignature(loadedDocument, page, certificate, "Signature", signatureField);
PdfBitmap signatureImage = new PdfBitmap(@"signature.jpg");
signatureField.Signature.Appearance.Normal.Graphics.DrawImage(signatureImage, new PointF(5, 5), new SizeF(100, 20));
//Save the document
loadedDocument.Save("Form.pdf");
//Close the document
loadedDocument.Close(true);
//This will open the PDF file so, the result will be seen in default PDF viewer
Process.Start("Form.pdf");
VB.NET
'Load the PDF document
Dim loadedDocument As PdfLoadedDocument = New PdfLoadedDocument("FormTemplate.pdf")
'Gets the first page of the document
Dim page As PdfLoadedPage = TryCast(loadedDocument.Pages(0), PdfLoadedPage)
'Get the loaded form
Dim form As PdfLoadedForm = loadedDocument.Form
'Fill the fields from the first page
TryCast(form.Fields("Name"), PdfLoadedTextBoxField).Text = "Simons"
TryCast(form.Fields("Email address"), PdfLoadedTextBoxField).Text = "simonsbistro@outlook.com"
TryCast(form.Fields("Phone"), PdfLoadedTextBoxField).Text = "31 12 34 56"
TryCast(form.Fields("Gender"), PdfLoadedRadioButtonListField).SelectedIndex = 0
TryCast(form.Fields("JobTitle"), PdfLoadedComboBoxField).SelectedIndex = 1
TryCast(form.Fields("Languages"), PdfLoadedListBoxField).SelectedIndex = New Integer(0) {2}
TryCast(form.Fields("Associate degree"), PdfLoadedCheckBoxField).Items(0).Checked = True
'Sign a PDF file
Dim signatureField As PdfLoadedSignatureField = TryCast(loadedDocument.Form.Fields(9), PdfLoadedSignatureField)
Dim certificate As PdfCertificate = New PdfCertificate("PDF.pfx", "syncfusion")
signatureField.Signature = New PdfSignature(loadedDocument, page, certificate, "Signature", signatureField)
Dim signatureImage As PdfBitmap = New PdfBitmap("signature.jpg")
signatureField.Signature.Appearance.Normal.Graphics.DrawImage(signatureImage, New PointF(5, 5), New SizeF(100, 20))
'Save the document
loadedDocument.Save("Form.pdf")
'Close the document
loadedDocument.Close(True)
'This will open the PDF file so, the result will be seen in default PDF viewer
Process.Start("Form.pdf")
You can download the work sample from PDFFormFillingSample.Zip.
By executing the program, you will get the PDF document as follows. 
Take a moment to peruse the documentation for PDF Form filling and sign a PDF file, where you will find other options like modifying existing form fields, filling form fields, removing editing capability, removing form fields, importing FDF file to PDF, export PDF file to FDF, adding actions to form fields, and adding a timestamp in digital signature.
Refer here to explore the rich set of Syncfusion Essential PDF features.
An online sample link to filling form fields to personalize PDF document.
Note:
Starting with v16.2.0.x, if you reference Syncfusion® assemblies from the trial setup or the NuGet feed, include a license key in your projects. Refer to the link to learn about generating and registering the Syncfusion® license key in your application to use the components without a trial message.
Conclusion:
I hope you enjoyed learning about how to fill form & sign a PDF file in C#, VB.NET.
You can refer to our Flutter PDF feature tour page to learn about its other groundbreaking features and documentation, and how to quickly get started with configuration specifications. You can also explore our Flutter PDF Flutter PDF examples to understand how to create and manipulate data.
For current customers, you can check out our components from the License and Downloads page. If you are new to Syncfusion®, you can try our 30-day free trial to explore our other controls.
If you have any queries or require clarifications, please let us know in the comments section below. You can also contact us through our support forums or feedback portal. We are always happy to assist you!
