Convert PDF to HTML in memory using C# and .NET
Document processing in modern applications increasingly requires dynamic file format conversion without saving intermediate files to disk.
One popular scenario is converting a PDF document to HTML for display in web interfaces or for further processing.
In this article, we'll explore how to implement in-memory PDF to HTML conversion in C# and .NET using the powerful
PDF Focus .NET component from SautinSoft library.
In-memory PDF to HTML conversion is a process in which the entire data stream is converted without
writing intermediate files to disk. This is critical in new applications where security, speed, and efficiency are paramount.
Key Benefits:
- Data Security: Avoiding the need to save files to disk reduces the risk of data leakage.
- Performance: Avoiding disk read/write operations speeds up processing.
- Integration: Easy implementation in ASP.NET applications, cloud solutions, APIs, and services.
Key Concept.
Using the PDF Focus API, you can load a PDF document from memory (for example, from a byte array or stream), convert it to HTML,
and retrieve the result as a string or stream—all without touching the file on disk.
This approach is widely used in various scenarios:
- Web applications and portals: displaying PDF documents in the browser without storing them on the server.
- Document processing and storage: automatically converting PDFs to HTML for indexing, searching, and further analysis.
- Mobile and cloud solutions: avoiding file system operations, reducing load and increasing speed.
- Integration with security systems: avoiding the use of file streams to reduce the risk of leaks.
Other important considerations and tips:
- Licensing: ensure you have a valid license key for PDF Focus .NET to use it in commercial applications.
- Performance: working with large files may require resource management and tuning API parameters.
- Converting complex documents: PDF Focus handles a wide range of PDFs well, but in rare cases, HTML post-processing may be required to remove artifacts.
- Error handling: Always implement exception handling to avoid data loss or crashes.
- HTML customization: You can further manage styles, CSS, and markup during conversion to tailor the result to your project's needs.
Complete code
GitHubusing System;
using System.IO;
namespace Sample
{
class Sample
{
static void Main(string[] args)
{
// Before starting, we recommend to get a free key:
// https://sautinsoft.com/start-for-free/
// Apply the key here:
// SautinSoft.PdfFocus.SetLicense("...");
ConvertPdfBytesToHtml();
//ConvertPdfStreamToHtml();
}
private static void ConvertPdfBytesToHtml()
{
// We need files only for demonstration purposes.
// The whole conversion process will be done in memory.
string pdfFile = Path.GetFullPath(@"..\..\..\simple text.pdf");
string htmlFile = "Result.html";
// Convert PDF to HTML in memory
SautinSoft.PdfFocus f = new SautinSoft.PdfFocus();
// Let's force the component to store images inside HTML document
// using base-64 encoding.
// Thus the component will not use HDD.
f.HtmlOptions.IncludeImageInHtml = true;
f.HtmlOptions.Title = "Simple text";
// Read a PDF document to byte array
// Assume that we already have the PDF as array of bytes.
byte[] pdf = File.ReadAllBytes(pdfFile);
f.OpenPdf(pdf);
if (f.PageCount > 0)
{
// Convert PDF to HTML in memory
string html = f.ToHtml();
// Save HTML to the file only for demonstration purpose.
if (html != null)
{
File.WriteAllText(htmlFile, html);
// Open the result for demonstration purposes.
System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(htmlFile) { UseShellExecute = true });
}
}
}
private static void ConvertPdfStreamToHtml()
{
// We need files only for demonstration purposes.
// The whole conversion process will be done in memory.
string pdfFile = Path.GetFullPath(@"..\..\..\simple text.pdf");
string htmlFile = "Result.html";
// Get your free key here:
// https://sautinsoft.com/start-for-free/
// Convert PDF to HTML in memory
SautinSoft.PdfFocus f = new SautinSoft.PdfFocus();
// Let's force the component to store images inside HTML document
// using base-64 encoding.
// Thus the component will not use HDD.
f.HtmlOptions.IncludeImageInHtml = true;
f.HtmlOptions.Title = "Simple text";
// Assume that we have a PDF document as Stream.
using (FileStream fs = File.OpenRead(pdfFile))
{
f.OpenPdf(fs);
if (f.PageCount > 0)
{
// Convert PDF to HTML to a MemoryStream.
using (MemoryStream msHtml = new MemoryStream())
{
int res = f.ToHtml(msHtml);
// Open the result for demonstration purposes.
if (res == 0)
{
File.WriteAllBytes(htmlFile, msHtml.ToArray());
System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(htmlFile) { UseShellExecute = true });
}
}
}
}
}
}
}
Imports System
Imports System.IO
Namespace Sample
Friend Class Sample
Shared Sub Main(ByVal args() As String)
' Before starting, we recommend to get a free key:
' https://sautinsoft.com/start-for-free/
' Apply the key here
' SautinSoft.PdfFocus.SetLicense("...");
ConvertPdfBytesToHtml()
'ConvertPdfStreamToHtml()
End Sub
Private Shared Sub ConvertPdfBytesToHtml()
' We need files only for demonstration purposes.
' The whole conversion process will be done in memory.
Dim pdfFile As String = Path.GetFullPath("..\..\..\simple text.pdf")
Dim htmlFile As String = "Result.html"
' Convert PDF to HTML in memory
Dim f As New SautinSoft.PdfFocus()
' Let's force the component to store images inside HTML document
' using base-64 encoding.
' Thus the component will not use HDD.
f.HtmlOptions.IncludeImageInHtml = True
f.HtmlOptions.Title = "Simple text"
' Read a PDF document to byte array
' Assume that we already have the PDF as array of bytes.
Dim pdf() As Byte = File.ReadAllBytes(pdfFile)
f.OpenPdf(pdf)
If f.PageCount > 0 Then
' Convert PDF to HTML in memory
Dim html As String = f.ToHtml()
' Save HTML to the file only for demonstration purpose.
If html IsNot Nothing Then
File.WriteAllText(htmlFile, html)
' Open the result for demonstration purposes.
System.Diagnostics.Process.Start(New System.Diagnostics.ProcessStartInfo(htmlFile) With {.UseShellExecute = True})
End If
End If
End Sub
Private Shared Sub ConvertPdfStreamToHtml()
' We need files only for demonstration purposes.
' The whole conversion process will be done in memory.
Dim pdfFile As String = Path.GetFullPath("..\..\..\simple text.pdf")
Dim htmlFile As String = "Result.html"
' Get your free key here:
' https://sautinsoft.com/start-for-free/
' Convert PDF to HTML in memory
Dim f As New SautinSoft.PdfFocus()
' Let's force the component to store images inside HTML document
' using base-64 encoding.
' Thus the component will not use HDD.
f.HtmlOptions.IncludeImageInHtml = True
f.HtmlOptions.Title = "Simple text"
' Assume that we have a PDF document as Stream.
Using fs As FileStream = File.OpenRead(pdfFile)
f.OpenPdf(fs)
If f.PageCount > 0 Then
' Convert PDF to HTML to a MemoryStream.
Using msHtml As New MemoryStream()
Dim res As Integer = f.ToHtml(msHtml)
' Open the result for demonstration purposes.
If res = 0 Then
File.WriteAllBytes(htmlFile, msHtml.ToArray())
System.Diagnostics.Process.Start(New System.Diagnostics.ProcessStartInfo(htmlFile) With {.UseShellExecute = True})
End If
End Using
End If
End Using
End Sub
End Class
End Namespace
If you need a new code example or have a question: email us at support@sautinsoft.com or ask at Online Chat (right-bottom corner of this page) or use the Form below: