The C# PDF Library

HTML to PDF

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;

// 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");

PM >Install-Package IronPdf

Install-Package IronPdf

MIGRATION GUIDES

How to Migrate from PDFBolt to IronPDF in C#

Curtis Chau

Updated: August 1, 2026

Migrating from PDFBolt to IronPDF moves your .NET PDF workflow from a cloud-only SaaS REST service to a self-hosted library with local document processing and no per-document quotas. This guide provides a step-by-step migration path that eliminates network dependencies, monthly usage caps, and external data transmission while adding PDF manipulation features that PDFBolt does not provide.

Why Migrate from PDFBolt to IronPDF

The Cloud-Only Problem

PDFBolt is a cloud-only SaaS platform exposed as a REST API; there is no official .NET SDK and no PDFBolt NuGet package. Integration is hand-rolled with HttpClient against https://api.pdfbolt.com/v1/direct. While convenient for quick prototypes, this architecture creates challenges for production applications:

Cloud-Only Processing: Every document passes through PDFBolt's servers - there is no self-hosted option, which can be a blocker for teams that need more control over data flow.
Data Privacy Considerations: Sensitive documents (contracts, medical records, financial data) are transmitted externally. Companies dealing with regulated data will have legitimate review concerns.
Usage Limits: The free tier is capped at 100 documents per month, 20 requests/minute, 1 concurrent request, which may not suffice for production workloads. Paid tiers (per pdfbolt.com/pricing) scale from $19/mo to $249/mo.
Network Dependency: Internet outages or PDFBolt downtime mean your PDF generation stops entirely.
Latency: Network round-trip adds seconds to every conversion compared to local processing.
Compliance Review: GDPR, HIPAA, and SOC2 audits typically require additional documentation when external document processing is involved.
API Key Security: Leaked API keys can result in unauthorized usage billed to your account.
Vendor Lock-in: Your application stops working if PDFBolt changes terms or shuts down.

PDFBolt vs IronPDF Comparison

Concern	PDFBolt	IronPDF
Data Location	External servers	Your servers only
Usage Limits	100 free/month, then tiered subscriptions	Unlimited
Internet Required	Yes, always	No
Latency	Network round-trip	Local
Compliance	Complex (external processing)	Simple (local processing)
Cost Model	Monthly subscription tiers ($19-$249/mo)	One-time or annual
Offline Operation	Impossible	Fully supported
API Key Risks	Leaked = billed	License key, no billing risk

IronPDF provides a self-hosted foundation on modern .NET that keeps document processing local and removes the dependency on an external cloud service.

Before You Start

Prerequisites

.NET Environment: .NET Framework 4.6.2+ or .NET Core 3.1+ / .NET 5/6/7/8/9+
NuGet Access: Ability to install NuGet packages
IronPDF License: Obtain your license key from ironpdf.com

NuGet Package Changes

PDFBolt has no official .NET SDK and no PDFBolt NuGet package, so there is nothing to uninstall. The PDFBolt-side cleanup is to delete the hand-rolled HttpClient wrapper and request/response DTOs. Then install IronPDF:

# Install IronPDF (replaces the hand-rolled HttpClient wrapper)
dotnet add package IronPdf

# Install IronPDF (replaces the hand-rolled HttpClient wrapper)
dotnet add package IronPdf

SHELL

License Configuration

// Add at application startup (Program.cs or Startup.cs)
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";

// Add at application startup (Program.cs or Startup.cs)
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";

' Add at application startup (Program.vb or Startup.vb)
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY"

' Add at application startup (Program.vb or Startup.vb)
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY"

Identify PDFBolt Usage

# Find all PDFBolt REST calls
grep -rE "api\.pdfbolt\.com|API-KEY|/v1/direct" --include="*.cs" .

# Find API key references
grep -r "PDFBOLT\|ApiKey" --include="*.cs" --include="*.json" --include="*.config" .

# Find all PDFBolt REST calls
grep -rE "api\.pdfbolt\.com|API-KEY|/v1/direct" --include="*.cs" .

# Find API key references
grep -r "PDFBOLT\|ApiKey" --include="*.cs" --include="*.json" --include="*.config" .

SHELL

Complete API Reference

Core Concept Mappings

PDFBolt (REST)	IronPDF
`HttpClient` + `API-KEY` header	`new ChromePdfRenderer()`
JSON request body	`renderer.RenderingOptions`
`POST https://api.pdfbolt.com/v1/direct`	`renderer.RenderHtmlAsPdf(...)` / `RenderUrlAsPdf(...)`
Response `byte[]`	`PdfDocument`

Conversion Method Mappings

PDFBolt (REST)	IronPDF
`POST /v1/direct` with `{ "html": <base64> }`	`renderer.RenderHtmlAsPdf(html)`
`POST /v1/direct` with `{ "url": "..." }`	`renderer.RenderUrlAsPdf(url)`

Output Method Mappings

PDFBolt (REST)	IronPDF
`await response.Content.ReadAsByteArrayAsync()` then `File.WriteAllBytes`	`pdf.SaveAs(path)`
`await response.Content.ReadAsByteArrayAsync()`	`pdf.BinaryData`

Page Configuration Mappings

PDFBolt JSON	IronPDF
`"format": "A4"`	`renderer.RenderingOptions.PaperSize = PdfPaperSize.A4`
`"margin": { "top": "20mm" }`	`renderer.RenderingOptions.MarginTop = 20`
`"margin": { "bottom": "20mm" }`	`renderer.RenderingOptions.MarginBottom = 20`
`"margin": { "left": "15mm" }`	`renderer.RenderingOptions.MarginLeft = 15`
`"margin": { "right": "15mm" }`	`renderer.RenderingOptions.MarginRight = 15`

Header/Footer Placeholder Mappings

PDFBolt (inside base64-encoded `headerTemplate` / `footerTemplate`)	IronPDF (`HtmlFragment` token)
`<span class="pageNumber"></span>`	`{page}`
`<span class="totalPages"></span>`	`{total-pages}`
`<span class="date"></span>`	`{date}`
`<span class="title"></span>`	`{html-title}`

Code Migration Examples

Example 1: Basic HTML to PDF

Before (PDFBolt - REST via HttpClient):

// REST API — no official .NET SDK; integrate via HttpClient.
// Docs: https://pdfbolt.com/docs/quick-start-guide/csharp
using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        var html = "<html><body><h1>Hello World</h1></body></html>";
        var payload = JsonSerializer.Serialize(new
        {
            html = Convert.ToBase64String(Encoding.UTF8.GetBytes(html))
        });

        using var http = new HttpClient();
        http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY");
        using var content = new StringContent(payload, Encoding.UTF8, "application/json");
        using var response = await http.PostAsync("https://api.pdfbolt.com/v1/direct", content);
        response.EnsureSuccessStatusCode();

        var pdfBytes = await response.Content.ReadAsByteArrayAsync();
        await File.WriteAllBytesAsync("output.pdf", pdfBytes);
    }
}

// REST API — no official .NET SDK; integrate via HttpClient.
// Docs: https://pdfbolt.com/docs/quick-start-guide/csharp
using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        var html = "<html><body><h1>Hello World</h1></body></html>";
        var payload = JsonSerializer.Serialize(new
        {
            html = Convert.ToBase64String(Encoding.UTF8.GetBytes(html))
        });

        using var http = new HttpClient();
        http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY");
        using var content = new StringContent(payload, Encoding.UTF8, "application/json");
        using var response = await http.PostAsync("https://api.pdfbolt.com/v1/direct", content);
        response.EnsureSuccessStatusCode();

        var pdfBytes = await response.Content.ReadAsByteArrayAsync();
        await File.WriteAllBytesAsync("output.pdf", pdfBytes);
    }
}

Imports System
Imports System.IO
Imports System.Net.Http
Imports System.Text
Imports System.Text.Json
Imports System.Threading.Tasks

Module Program
    Async Function Main() As Task
        Dim html As String = "<html><body><h1>Hello World</h1></body></html>"
        Dim payload As String = JsonSerializer.Serialize(New With {
            .html = Convert.ToBase64String(Encoding.UTF8.GetBytes(html))
        })

        Using http As New HttpClient()
            http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY")
            Using content As New StringContent(payload, Encoding.UTF8, "application/json")
                Using response As HttpResponseMessage = Await http.PostAsync("https://api.pdfbolt.com/v1/direct", content)
                    response.EnsureSuccessStatusCode()

                    Dim pdfBytes As Byte() = Await response.Content.ReadAsByteArrayAsync()
                    Await File.WriteAllBytesAsync("output.pdf", pdfBytes)
                End Using
            End Using
        End Using
    End Function
End Module

Imports System
Imports System.IO
Imports System.Net.Http
Imports System.Text
Imports System.Text.Json
Imports System.Threading.Tasks

Module Program
    Async Function Main() As Task
        Dim html As String = "<html><body><h1>Hello World</h1></body></html>"
        Dim payload As String = JsonSerializer.Serialize(New With {
            .html = Convert.ToBase64String(Encoding.UTF8.GetBytes(html))
        })

        Using http As New HttpClient()
            http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY")
            Using content As New StringContent(payload, Encoding.UTF8, "application/json")
                Using response As HttpResponseMessage = Await http.PostAsync("https://api.pdfbolt.com/v1/direct", content)
                    response.EnsureSuccessStatusCode()

                    Dim pdfBytes As Byte() = Await response.Content.ReadAsByteArrayAsync()
                    Await File.WriteAllBytesAsync("output.pdf", pdfBytes)
                End Using
            End Using
        End Using
    End Function
End Module

After (IronPDF):

// NuGet: Install-Package IronPdf
using IronPdf;
using System.IO;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var html = "<html><body><h1>Hello World</h1></body></html>";
        var pdf = renderer.RenderHtmlAsPdf(html);
        pdf.SaveAs("output.pdf");
    }
}

// NuGet: Install-Package IronPdf
using IronPdf;
using System.IO;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var html = "<html><body><h1>Hello World</h1></body></html>";
        var pdf = renderer.RenderHtmlAsPdf(html);
        pdf.SaveAs("output.pdf");
    }
}

Imports IronPdf
Imports System.IO

Class Program
    Shared Sub Main()
        Dim renderer = New ChromePdfRenderer()
        Dim html = "<html><body><h1>Hello World</h1></body></html>"
        Dim pdf = renderer.RenderHtmlAsPdf(html)
        pdf.SaveAs("output.pdf")
    End Sub
End Class

Imports IronPdf
Imports System.IO

Class Program
    Shared Sub Main()
        Dim renderer = New ChromePdfRenderer()
        Dim html = "<html><body><h1>Hello World</h1></body></html>"
        Dim pdf = renderer.RenderHtmlAsPdf(html)
        pdf.SaveAs("output.pdf")
    End Sub
End Class

The structural difference is the integration model. PDFBolt requires you to base64-encode the HTML, build a JSON payload, set the API-KEY header, POST to https://api.pdfbolt.com/v1/direct, await the response, and write the returned bytes to disk yourself.

IronPDF's ChromePdfRenderer.RenderHtmlAsPdf() returns a PdfDocument object with a built-in SaveAs() method. The object-oriented model lets you manipulate the PDF (add watermarks, merge documents, apply security) before saving. If you need the raw bytes for compatibility with existing code, use pdf.BinaryData. See the HTML to PDF documentation for additional rendering options.

Example 2: URL to PDF Conversion

Before (PDFBolt - REST via HttpClient):

// REST API — no official .NET SDK; integrate via HttpClient.
// Docs: https://pdfbolt.com/docs/quick-start-guide/csharp
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        var payload = JsonSerializer.Serialize(new { url = "https://www.example.com" });

        using var http = new HttpClient();
        http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY");
        using var content = new StringContent(payload, Encoding.UTF8, "application/json");
        using var response = await http.PostAsync("https://api.pdfbolt.com/v1/direct", content);
        response.EnsureSuccessStatusCode();

        var pdfBytes = await response.Content.ReadAsByteArrayAsync();
        await File.WriteAllBytesAsync("webpage.pdf", pdfBytes);
    }
}

// REST API — no official .NET SDK; integrate via HttpClient.
// Docs: https://pdfbolt.com/docs/quick-start-guide/csharp
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        var payload = JsonSerializer.Serialize(new { url = "https://www.example.com" });

        using var http = new HttpClient();
        http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY");
        using var content = new StringContent(payload, Encoding.UTF8, "application/json");
        using var response = await http.PostAsync("https://api.pdfbolt.com/v1/direct", content);
        response.EnsureSuccessStatusCode();

        var pdfBytes = await response.Content.ReadAsByteArrayAsync();
        await File.WriteAllBytesAsync("webpage.pdf", pdfBytes);
    }
}

Imports System.IO
Imports System.Net.Http
Imports System.Text
Imports System.Text.Json
Imports System.Threading.Tasks

Module Program
    Async Function Main() As Task
        Dim payload = JsonSerializer.Serialize(New With {.url = "https://www.example.com"})

        Using http As New HttpClient()
            http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY")
            Using content As New StringContent(payload, Encoding.UTF8, "application/json")
                Using response As HttpResponseMessage = Await http.PostAsync("https://api.pdfbolt.com/v1/direct", content)
                    response.EnsureSuccessStatusCode()

                    Dim pdfBytes As Byte() = Await response.Content.ReadAsByteArrayAsync()
                    Await File.WriteAllBytesAsync("webpage.pdf", pdfBytes)
                End Using
            End Using
        End Using
    End Function
End Module

Imports System.IO
Imports System.Net.Http
Imports System.Text
Imports System.Text.Json
Imports System.Threading.Tasks

Module Program
    Async Function Main() As Task
        Dim payload = JsonSerializer.Serialize(New With {.url = "https://www.example.com"})

        Using http As New HttpClient()
            http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY")
            Using content As New StringContent(payload, Encoding.UTF8, "application/json")
                Using response As HttpResponseMessage = Await http.PostAsync("https://api.pdfbolt.com/v1/direct", content)
                    response.EnsureSuccessStatusCode()

                    Dim pdfBytes As Byte() = Await response.Content.ReadAsByteArrayAsync()
                    Await File.WriteAllBytesAsync("webpage.pdf", pdfBytes)
                End Using
            End Using
        End Using
    End Function
End Module

After (IronPDF):

// NuGet: Install-Package IronPdf
using IronPdf;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderUrlAsPdf("https://www.example.com");
        pdf.SaveAs("webpage.pdf");
    }
}

// NuGet: Install-Package IronPdf
using IronPdf;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        var pdf = renderer.RenderUrlAsPdf("https://www.example.com");
        pdf.SaveAs("webpage.pdf");
    }
}

Imports IronPdf

Class Program
    Shared Sub Main()
        Dim renderer As New ChromePdfRenderer()
        Dim pdf = renderer.RenderUrlAsPdf("https://www.example.com")
        pdf.SaveAs("webpage.pdf")
    End Sub
End Class

Imports IronPdf

Class Program
    Shared Sub Main()
        Dim renderer As New ChromePdfRenderer()
        Dim pdf = renderer.RenderUrlAsPdf("https://www.example.com")
        pdf.SaveAs("webpage.pdf")
    End Sub
End Class

On the PDFBolt side, URL conversion still requires the full REST round-trip: build the JSON body, set the API key header, await the POST, and write the response bytes. Even though you're already pointing at a public URL, the fetch and the render both happen on PDFBolt's servers.

IronPDF's RenderUrlAsPdf() returns a PdfDocument with the built-in SaveAs() method. The key advantage is that IronPDF performs the URL fetch and PDF rendering locally - no document data leaves your infrastructure. Learn more about URL to PDF conversion.

Example 3: HTML File with Custom Page Settings

Before (PDFBolt - REST via HttpClient):

// REST API — no official .NET SDK; integrate via HttpClient.
// Docs: https://pdfbolt.com/docs/parameters
using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        var html = await File.ReadAllTextAsync("input.html");
        var payload = JsonSerializer.Serialize(new
        {
            html = Convert.ToBase64String(Encoding.UTF8.GetBytes(html)),
            format = "A4",
            margin = new { top = "20mm", bottom = "20mm" },
            printBackground = true
        });

        using var http = new HttpClient();
        http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY");
        using var content = new StringContent(payload, Encoding.UTF8, "application/json");
        using var response = await http.PostAsync("https://api.pdfbolt.com/v1/direct", content);
        response.EnsureSuccessStatusCode();

        var pdfBytes = await response.Content.ReadAsByteArrayAsync();
        await File.WriteAllBytesAsync("output.pdf", pdfBytes);
    }
}

// REST API — no official .NET SDK; integrate via HttpClient.
// Docs: https://pdfbolt.com/docs/parameters
using System;
using System.IO;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        var html = await File.ReadAllTextAsync("input.html");
        var payload = JsonSerializer.Serialize(new
        {
            html = Convert.ToBase64String(Encoding.UTF8.GetBytes(html)),
            format = "A4",
            margin = new { top = "20mm", bottom = "20mm" },
            printBackground = true
        });

        using var http = new HttpClient();
        http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY");
        using var content = new StringContent(payload, Encoding.UTF8, "application/json");
        using var response = await http.PostAsync("https://api.pdfbolt.com/v1/direct", content);
        response.EnsureSuccessStatusCode();

        var pdfBytes = await response.Content.ReadAsByteArrayAsync();
        await File.WriteAllBytesAsync("output.pdf", pdfBytes);
    }
}

Imports System
Imports System.IO
Imports System.Net.Http
Imports System.Text
Imports System.Text.Json
Imports System.Threading.Tasks

Module Program
    Async Function Main() As Task
        Dim html = Await File.ReadAllTextAsync("input.html")
        Dim payload = JsonSerializer.Serialize(New With {
            .html = Convert.ToBase64String(Encoding.UTF8.GetBytes(html)),
            .format = "A4",
            .margin = New With {.top = "20mm", .bottom = "20mm"},
            .printBackground = True
        })

        Using http As New HttpClient()
            http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY")
            Using content As New StringContent(payload, Encoding.UTF8, "application/json")
                Using response As HttpResponseMessage = Await http.PostAsync("https://api.pdfbolt.com/v1/direct", content)
                    response.EnsureSuccessStatusCode()

                    Dim pdfBytes = Await response.Content.ReadAsByteArrayAsync()
                    Await File.WriteAllBytesAsync("output.pdf", pdfBytes)
                End Using
            End Using
        End Using
    End Function
End Module

Imports System
Imports System.IO
Imports System.Net.Http
Imports System.Text
Imports System.Text.Json
Imports System.Threading.Tasks

Module Program
    Async Function Main() As Task
        Dim html = Await File.ReadAllTextAsync("input.html")
        Dim payload = JsonSerializer.Serialize(New With {
            .html = Convert.ToBase64String(Encoding.UTF8.GetBytes(html)),
            .format = "A4",
            .margin = New With {.top = "20mm", .bottom = "20mm"},
            .printBackground = True
        })

        Using http As New HttpClient()
            http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY")
            Using content As New StringContent(payload, Encoding.UTF8, "application/json")
                Using response As HttpResponseMessage = Await http.PostAsync("https://api.pdfbolt.com/v1/direct", content)
                    response.EnsureSuccessStatusCode()

                    Dim pdfBytes = Await response.Content.ReadAsByteArrayAsync()
                    Await File.WriteAllBytesAsync("output.pdf", pdfBytes)
                End Using
            End Using
        End Using
    End Function
End Module

After (IronPDF):

// NuGet: Install-Package IronPdf
using IronPdf;
using IronPdf.Rendering;
using System.IO;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;
        renderer.RenderingOptions.MarginTop = 20;
        renderer.RenderingOptions.MarginBottom = 20;
        var html = File.ReadAllText("input.html");
        var pdf = renderer.RenderHtmlAsPdf(html);
        pdf.SaveAs("output.pdf");
    }
}

// NuGet: Install-Package IronPdf
using IronPdf;
using IronPdf.Rendering;
using System.IO;

class Program
{
    static void Main()
    {
        var renderer = new ChromePdfRenderer();
        renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;
        renderer.RenderingOptions.MarginTop = 20;
        renderer.RenderingOptions.MarginBottom = 20;
        var html = File.ReadAllText("input.html");
        var pdf = renderer.RenderHtmlAsPdf(html);
        pdf.SaveAs("output.pdf");
    }
}

Imports IronPdf
Imports IronPdf.Rendering
Imports System.IO

Class Program
    Shared Sub Main()
        Dim renderer = New ChromePdfRenderer()
        renderer.RenderingOptions.PaperSize = PdfPaperSize.A4
        renderer.RenderingOptions.MarginTop = 20
        renderer.RenderingOptions.MarginBottom = 20
        Dim html = File.ReadAllText("input.html")
        Dim pdf = renderer.RenderHtmlAsPdf(html)
        pdf.SaveAs("output.pdf")
    End Sub
End Class

Imports IronPdf
Imports IronPdf.Rendering
Imports System.IO

Class Program
    Shared Sub Main()
        Dim renderer = New ChromePdfRenderer()
        renderer.RenderingOptions.PaperSize = PdfPaperSize.A4
        renderer.RenderingOptions.MarginTop = 20
        renderer.RenderingOptions.MarginBottom = 20
        Dim html = File.ReadAllText("input.html")
        Dim pdf = renderer.RenderHtmlAsPdf(html)
        pdf.SaveAs("output.pdf")
    End Sub
End Class

This example shows the page configuration mapping. PDFBolt accepts top-level format plus a nested margin object whose values are CSS-style strings ("20mm"). IronPDF uses a RenderingOptions object on the renderer with strongly-typed properties.

The key mappings:

"format": "A4" → PdfPaperSize.A4 (strongly-typed enum)
"margin": { "top": "20mm" } → RenderingOptions.MarginTop = 20 (numeric mm)

IronPDF margins are always numeric millimeters, so PDFBolt CSS-unit strings like "20mm" map directly. The IronPdf.Rendering namespace is required for access to the PdfPaperSize enum. For additional page configuration, see the rendering options documentation.

Critical Migration Notes

Return Type Change

PDFBolt's /v1/direct endpoint returns the raw PDF as the HTTP response body; IronPDF returns a PdfDocument:

// PDFBolt pattern:
var pdfBytes = await response.Content.ReadAsByteArrayAsync();
await File.WriteAllBytesAsync("output.pdf", pdfBytes);

// IronPDF pattern:
var pdf = renderer.RenderHtmlAsPdf(html);
pdf.SaveAs("output.pdf");

// Or if you need bytes:
byte[] pdfBytes = renderer.RenderHtmlAsPdf(html).BinaryData;

// PDFBolt pattern:
var pdfBytes = await response.Content.ReadAsByteArrayAsync();
await File.WriteAllBytesAsync("output.pdf", pdfBytes);

// IronPDF pattern:
var pdf = renderer.RenderHtmlAsPdf(html);
pdf.SaveAs("output.pdf");

// Or if you need bytes:
byte[] pdfBytes = renderer.RenderHtmlAsPdf(html).BinaryData;

Imports System.IO
Imports System.Net.Http

' PDFBolt pattern:
Dim pdfBytes = Await response.Content.ReadAsByteArrayAsync()
Await File.WriteAllBytesAsync("output.pdf", pdfBytes)

' IronPDF pattern:
Dim pdf = renderer.RenderHtmlAsPdf(html)
pdf.SaveAs("output.pdf")

' Or if you need bytes:
Dim pdfBytes As Byte() = renderer.RenderHtmlAsPdf(html).BinaryData

Imports System.IO
Imports System.Net.Http

' PDFBolt pattern:
Dim pdfBytes = Await response.Content.ReadAsByteArrayAsync()
Await File.WriteAllBytesAsync("output.pdf", pdfBytes)

' IronPDF pattern:
Dim pdf = renderer.RenderHtmlAsPdf(html)
pdf.SaveAs("output.pdf")

' Or if you need bytes:
Dim pdfBytes As Byte() = renderer.RenderHtmlAsPdf(html).BinaryData

Integration Model Change

The integration shape changes from REST client to in-process library:

// PDFBolt
using var http = new HttpClient();
http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY");
// ... build JSON, POST to https://api.pdfbolt.com/v1/direct

// IronPDF
var renderer = new ChromePdfRenderer();

// PDFBolt
using var http = new HttpClient();
http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY");
// ... build JSON, POST to https://api.pdfbolt.com/v1/direct

// IronPDF
var renderer = new ChromePdfRenderer();

Imports System.Net.Http

' PDFBolt
Using http As New HttpClient()
    http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY")
    ' ... build JSON, POST to https://api.pdfbolt.com/v1/direct
End Using

' IronPDF
Dim renderer As New ChromePdfRenderer()

Imports System.Net.Http

' PDFBolt
Using http As New HttpClient()
    http.DefaultRequestHeaders.Add("API-KEY", "YOUR-PDFBOLT-API-KEY")
    ' ... build JSON, POST to https://api.pdfbolt.com/v1/direct
End Using

' IronPDF
Dim renderer As New ChromePdfRenderer()

Configuration Pattern Change

PDFBolt configuration is JSON fields on the request body; IronPDF uses RenderingOptions:

// PDFBolt: JSON request fields
new { format = "A4", margin = new { top = "20mm" } }

// IronPDF: RenderingOptions properties
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;
renderer.RenderingOptions.MarginTop = 20;

// PDFBolt: JSON request fields
new { format = "A4", margin = new { top = "20mm" } }

// IronPDF: RenderingOptions properties
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;
renderer.RenderingOptions.MarginTop = 20;

' PDFBolt: JSON request fields
New With {Key .format = "A4", Key .margin = New With {Key .top = "20mm"}}

' IronPDF: RenderingOptions properties
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4
renderer.RenderingOptions.MarginTop = 20

' PDFBolt: JSON request fields
New With {Key .format = "A4", Key .margin = New With {Key .top = "20mm"}}

' IronPDF: RenderingOptions properties
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4
renderer.RenderingOptions.MarginTop = 20

API Key Elimination

PDFBolt requires an API-KEY header on every request; IronPDF uses a one-time license key:

// PDFBolt: API key per HTTP call (security risk if leaked)
http.DefaultRequestHeaders.Add("API-KEY", config["PDFBolt:ApiKey"]);

// IronPDF: License key once at startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";
var renderer = new ChromePdfRenderer();

// PDFBolt: API key per HTTP call (security risk if leaked)
http.DefaultRequestHeaders.Add("API-KEY", config["PDFBolt:ApiKey"]);

// IronPDF: License key once at startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY";
var renderer = new ChromePdfRenderer();

' PDFBolt: API key per HTTP call (security risk if leaked)
http.DefaultRequestHeaders.Add("API-KEY", config("PDFBolt:ApiKey"))

' IronPDF: License key once at startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY"
Dim renderer As New ChromePdfRenderer()

' PDFBolt: API key per HTTP call (security risk if leaked)
http.DefaultRequestHeaders.Add("API-KEY", config("PDFBolt:ApiKey"))

' IronPDF: License key once at startup
IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY"
Dim renderer As New ChromePdfRenderer()

Remove Network Error Handling

Local processing means no network errors to handle:

// PDFBolt: Network error handling required
catch (HttpRequestException ex)
catch (TaskCanceledException)
catch (TimeoutException)

// IronPDF: Remove network-specific catches entirely

// PDFBolt: Network error handling required
catch (HttpRequestException ex)
catch (TaskCanceledException)
catch (TimeoutException)

// IronPDF: Remove network-specific catches entirely

net

net

New Capabilities Available

After migrating to IronPDF, you gain capabilities that PDFBolt does not provide:

// PDF Merging (not available in PDFBolt)
var merged = PdfDocument.Merge(pdf1, pdf2);

// Watermarks (not available in PDFBolt)
pdf.ApplyWatermark("<h1 style='opacity:0.3;'>DRAFT</h1>");

// Password Protection (not available in PDFBolt)
pdf.SecuritySettings.UserPassword = "secret";

// Text Extraction (not available in PDFBolt)
string text = pdf.ExtractAllText();

// PDF to Images (not available in PDFBolt)
pdf.RasterizeToImageFiles("page_*.png");

// PDF Merging (not available in PDFBolt)
var merged = PdfDocument.Merge(pdf1, pdf2);

// Watermarks (not available in PDFBolt)
pdf.ApplyWatermark("<h1 style='opacity:0.3;'>DRAFT</h1>");

// Password Protection (not available in PDFBolt)
pdf.SecuritySettings.UserPassword = "secret";

// Text Extraction (not available in PDFBolt)
string text = pdf.ExtractAllText();

// PDF to Images (not available in PDFBolt)
pdf.RasterizeToImageFiles("page_*.png");

' PDF Merging (not available in PDFBolt)
Dim merged = PdfDocument.Merge(pdf1, pdf2)

' Watermarks (not available in PDFBolt)
pdf.ApplyWatermark("<h1 style='opacity:0.3;'>DRAFT</h1>")

' Password Protection (not available in PDFBolt)
pdf.SecuritySettings.UserPassword = "secret"

' Text Extraction (not available in PDFBolt)
Dim text As String = pdf.ExtractAllText()

' PDF to Images (not available in PDFBolt)
pdf.RasterizeToImageFiles("page_*.png")

' PDF Merging (not available in PDFBolt)
Dim merged = PdfDocument.Merge(pdf1, pdf2)

' Watermarks (not available in PDFBolt)
pdf.ApplyWatermark("<h1 style='opacity:0.3;'>DRAFT</h1>")

' Password Protection (not available in PDFBolt)
pdf.SecuritySettings.UserPassword = "secret"

' Text Extraction (not available in PDFBolt)
Dim text As String = pdf.ExtractAllText()

' PDF to Images (not available in PDFBolt)
pdf.RasterizeToImageFiles("page_*.png")

Troubleshooting

Issue 1: No `PDFBolt` Package on NuGet

Problem: Looking for using PDFBolt; / new HtmlToPdfConverter() in IronPDF.

Solution: PDFBolt has no .NET SDK - its integration is HttpClient against https://api.pdfbolt.com/v1/direct. IronPDF replaces that wrapper entirely with ChromePdfRenderer:

// IronPDF
var renderer = new ChromePdfRenderer();

// IronPDF
var renderer = new ChromePdfRenderer();

' IronPDF
Dim renderer As New ChromePdfRenderer()

' IronPDF
Dim renderer As New ChromePdfRenderer()

Issue 2: Where Did `ConvertHtmlString` Go?

Problem: Migrating an in-house PDFBolt wrapper that exposed a ConvertHtmlString(html) method.

Solution: Use RenderHtmlAsPdf():

// IronPDF
var pdf = renderer.RenderHtmlAsPdf(html);

// IronPDF
var pdf = renderer.RenderHtmlAsPdf(html);

net

net

Issue 3: Where Did `ConvertUrl` Go?

Problem: Migrating an in-house PDFBolt wrapper that exposed a ConvertUrl(url) method.

Solution: Use RenderUrlAsPdf():

// IronPDF
var pdf = renderer.RenderUrlAsPdf(url);

// IronPDF
var pdf = renderer.RenderUrlAsPdf(url);

net

net

Issue 4: `format` JSON Field → Enum

Problem: Translating PDFBolt's "format": "A4" JSON field.

Solution: Use PdfPaperSize from IronPdf.Rendering:

// IronPDF
using IronPdf.Rendering;
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;

// IronPDF
using IronPdf.Rendering;
renderer.RenderingOptions.PaperSize = PdfPaperSize.A4;

Imports IronPdf.Rendering

renderer.RenderingOptions.PaperSize = PdfPaperSize.A4

Imports IronPdf.Rendering

renderer.RenderingOptions.PaperSize = PdfPaperSize.A4

Issue 5: First PDF Generation Is Slow

Problem: Initial render takes longer than expected.

Solution: The Chromium engine initializes on first use. Pre-warm if needed:

// Warm up during application startup
var renderer = new ChromePdfRenderer();
renderer.RenderHtmlAsPdf("<html><body></body></html>");

// Warm up during application startup
var renderer = new ChromePdfRenderer();
renderer.RenderHtmlAsPdf("<html><body></body></html>");

' Warm up during application startup
Dim renderer As New ChromePdfRenderer()
renderer.RenderHtmlAsPdf("<html><body></body></html>")

' Warm up during application startup
Dim renderer As New ChromePdfRenderer()
renderer.RenderHtmlAsPdf("<html><body></body></html>")

Migration Checklist

Pre-Migration

Inventory all PDFBolt REST calls in codebase (api.pdfbolt.com)
Document current JSON request fields (format, margin, printBackground, headerTemplate, etc.)
Identify API key management code to remove
List 429 / quota retry handling to delete
Obtain IronPDF license key

Package Changes

Delete the hand-rolled PDFBolt HttpClient wrapper and DTOs (no NuGet package to uninstall)
Install IronPdf NuGet package: dotnet add package IronPdf
Add using IronPdf; namespace
Add using IronPdf.Rendering; for paper size enums

Code Changes

Add license key configuration at startup
Replace the HttpClient + API-KEY integration with ChromePdfRenderer
Replace POST /v1/direct with RenderHtmlAsPdf() / RenderUrlAsPdf()
Replace await response.Content.ReadAsByteArrayAsync() + File.WriteAllBytes() with pdf.SaveAs() (or pdf.BinaryData if bytes are still needed)
Map "format" / "margin" JSON fields to RenderingOptions.PaperSize / RenderingOptions.MarginTop etc.
Remove API key management code
Remove 429 / rate limit handling
Remove network error handling

Post-Migration

Delete API key from configuration files
Remove API key from secret managers
Run all tests comparing PDF output
Verify page sizes and margins render correctly
Consider adding new capabilities (watermarks, security, merging)

Please note: PDFBolt is a registered trademark of its respective owner. This site is not affiliated with, endorsed by, or sponsored by PDFBolt. All product names, logos, and brands are property of their respective owners. Comparisons are for informational purposes only and reflect publicly available information at the time of writing.

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.

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