- Virtual PDF Printer SDK: Automatically Print to PDF and Upload PDF Files to Your Server
- Build a Virtual PDF Printer with Delphi or Any Programming Language: How to Process PDF Files After Printing
Many developers want to build a virtual PDF printer that can save printed documents as PDF files and then send them to a server. A common question is:
Can a virtual PDF printer create the PDF directly in memory without saving it to disk?
The short answer is no. Windows printing works through the print spooler, so temporary files are always created during the printing process. However, there is an easy and secure way to handle this.
This article explains how a PDF Virtual Printer SDK works, what programming languages you can use, and how to upload PDF files to your server after printing.
What Programming Languages Does a PDF Virtual Printer SDK Support?
One of the biggest advantages of a standard Windows virtual printer is that it is not tied to one programming language.
You can use it with almost any language, including:
| Programming Language | Supported |
|---|---|
| Delphi | ✅ Yes |
| C++ | ✅ Yes |
| C# | ✅ Yes |
| VB.NET | ✅ Yes |
| Python | ✅ Yes |
| Java | ✅ Yes |
| Go | ✅ Yes |
| Rust | ✅ Yes |
| PHP | ✅ Yes |
| Any language that can edit files or run programs | ✅ Yes |
The virtual printer works like a normal Windows printer. Your application communicates with it through a simple configuration file instead of a language-specific API.
How Does the Virtual PDF Printer Work?
The printing process is simple.
Application
│
▼
Windows Print Spooler
│
▼
Virtual PDF Printer
│
▼
Generate PDF
│
▼
Run Your Program
│
▼
Upload PDF
│
▼
Delete Temporary PDFYour application only needs to decide what happens after the PDF is created.
Automatically Print to PDF and Upload PDF Files to Your Server
The most popular use of a Virtual PDF Printer SDK is to automatically create a PDF file and send it to your own server.
Users simply print as they normally do. They do not need to save the PDF manually or choose a folder. Everything happens in the background.
The workflow looks like this:
Print Document
│
▼
Virtual PDF Printer
│
▼
Create PDF File
│
▼
Run Your Application
│
▼
Upload PDF to Server
│
▼
Delete Temporary FileThis workflow is perfect for:
| Use Case | Benefit |
|---|---|
| Document Management System | Automatically archive printed documents |
| ERP Software | Save invoices to your server |
| CRM System | Attach customer documents automatically |
| Fax Software | Upload PDF before sending a fax |
| Medical System | Store patient documents securely |
| Cloud Storage | Upload directly to AWS, Azure, Google Cloud or your own server |
Your users only need to click Print.
The Virtual PDF Printer automatically:
- creates the PDF file
- starts your own application
- uploads the PDF using your API
- deletes the temporary PDF file if needed
There are no extra steps for the user.
This makes it easy to build a complete Print to PDF and Upload to Server solution.
Whether your application is written in Delphi, C#, C++, Java, Python, or another language, the workflow is exactly the same.
Why Developers Choose This Workflow
Many developers do not need a PDF editor. They simply need a way to capture printed documents and send them to a server automatically.
Compared with manual PDF saving, this workflow saves time and reduces user mistakes.
| Manual PDF Saving | Automatic PDF Upload |
|---|---|
| User selects folder | Everything is automatic |
| User names the file | Filename is generated automatically |
| User uploads the PDF | Upload starts automatically |
| Easy to forget a step | No user action required |
| Slower workflow | Faster and more reliable |
For companies that process hundreds or thousands of printed documents every day, automatic PDF creation and server upload can greatly improve efficiency while keeping the user's printing experience simple.
Control Everything with One Config File
The printer behavior is controlled by a single config.ini file.
For example:
[Options]
OutputPDFFile=%APPFOLDER%\%ORIGINAL_FILENAME%.pdf
RunEXE=<%APPFOLDER%\YourApp.exe> <%FULL_FILENAME%>
ServerURL=
PrinterName=VeryPDF PDFPrinterYou can change this file from your own application before printing.
This makes it easy to:
- Change the output folder
- Change the PDF file name
- Run your own program
- Start another workflow
- Upload files
- Add security
- Convert PDF to images
- Stamp PDF files
Can I Use Delphi?
Yes.
Many developers use Delphi together with a virtual PDF printer.
The workflow is very simple.
- User prints a document.
- The virtual printer creates the PDF.
- The printer starts your Delphi EXE.
- Your Delphi program receives the PDF filename.
- Delphi uploads the PDF.
- Delphi deletes the local PDF file.
Example:
RunEXE=<%APPFOLDER%\MyDelphiApp.exe> <%FULL_FILENAME%>Your Delphi program receives the generated PDF path as a command-line parameter.
Can I Create the PDF in Memory Without Saving to Disk?
This is probably the most common question.
Unfortunately, Windows does not allow this.
The Windows printing system always creates spool files on disk.
The process looks like this:
Application
│
▼
Print Spooler (Disk)
│
▼
Virtual Printer
│
▼
PDF FileThe virtual printer cannot skip the Windows spooler.
This is part of the Windows printing system, not a limitation of the virtual printer.
Is There a Secure Alternative?
Yes.
Many companies use this workflow.
| Step | What Happens |
|---|---|
| Print document | Windows creates spool files |
| Generate PDF | PDF is saved temporarily |
| Load PDF into memory | Your program reads the PDF |
| Upload to server | Send through your API |
| Delete PDF | Remove the temporary file immediately |
The PDF only stays on disk for a very short time.
This is the standard solution used by many secure document systems.
Example Workflow
Suppose a user prints an invoice.
The process could look like this.
Print Invoice
│
▼
VeryPDF Virtual Printer
│
▼
invoice.pdf
│
▼
Delphi EXE Starts
│
▼
Read PDF into Memory
│
▼
Upload with HTTPS
│
▼
Delete invoice.pdfFrom the user's point of view, everything happens automatically.
Can My Program Ask the User for More Information?
Yes.
Your program can display its own dialog after printing.
For example, you can ask for:
- Fax number
- Customer ID
- Email address
- Project number
- Department
- Notes
After the user enters the information, your program can upload both the PDF and the extra data to your server.
Can I Upload the PDF Using My Own API?
Yes.
Your application has full control.
For example, your program can:
- Upload with REST API
- Upload with SOAP
- Upload with HTTPS
- Upload with FTP
- Save to cloud storage
- Save to SharePoint
- Save to SQL Server
- Save to AWS S3
- Save to Azure Storage
The virtual printer only creates the PDF.
Your own application decides what happens next.
Why Use a Config File Instead of a Programming API?
A configuration file makes integration much easier.
| Config File | Programming API |
|---|---|
| Easy to edit | Requires coding |
| Works with every language | Language specific |
| Easy to deploy | Extra libraries |
| Easy to automate | More development work |
Many developers simply update the config file before each print job.
Typical Business Workflow
Many companies use a process like this.
User Prints
│
▼
Virtual PDF Printer
│
▼
PDF Created
│
▼
Custom EXE Starts
│
▼
Read PDF
│
▼
Add Customer Information
│
▼
Upload to Server
│
▼
Delete Local PDFThis works well for:
- Document management systems
- Fax software
- Medical systems
- Insurance software
- Accounting software
- ERP systems
- CRM systems
- Workflow automation
Advantages
| Feature | Benefit |
|---|---|
| Works with Delphi | No extra SDK needed |
| Supports all programming languages | Easy integration |
| Config file control | Simple setup |
| Runs your own EXE | Complete customization |
| Upload using your own API | Full control |
| Automatic workflow | Less user work |
| Temporary PDF | Easy to remove after upload |
Frequently Asked Questions
1. Does the Virtual PDF Printer support Delphi?
Yes. Delphi works very well with the virtual printer. Your Delphi application can receive the generated PDF and process it automatically.
2. Can I use C# instead of Delphi?
Yes. You can use C#, C++, VB.NET, Python, Java, Go, Rust, or almost any programming language.
3. Does the printer include a programming API?
The printer is mainly controlled through a simple config.ini file, so it is not limited to one programming language.
4. Can I upload the PDF to my own server?
Yes. Your application can upload the PDF using your own API.
5. Can my application ask the user for a fax number?
Yes. After printing, your application can display any dialog box before uploading the PDF.
6. Can the PDF be created only in memory?
No. Windows printing always creates spool files on disk before the PDF is generated.
7. Is saving the PDF temporarily on disk secure?
Yes. Your application can load the PDF into memory, upload it immediately, and then delete the temporary file.
8. Can the printer automatically start my application?
Yes. You can use the RunEXE option to launch your own program after the PDF is created.
9. Can I change the PDF filename?
Yes. The output filename is controlled through the configuration file.
10. Can I automate the entire printing process?
Yes. Printing, PDF creation, running your application, uploading the PDF, and deleting temporary files can all happen automatically.
11. Can I save the PDF to cloud storage?
Yes. Your application can upload the PDF to AWS, Azure, Google Cloud, SharePoint, or any other storage service.
12. Is this suitable for enterprise document workflows?
Yes. Many business applications use this method to automate PDF creation, document upload, and workflow processing while keeping full control of the data.
Final Thoughts
If you need to build a Virtual PDF Printer that works with Delphi, C#, C++, Python, Java, or any other programming language, a standard Windows virtual printer is a simple and flexible solution.
Although Windows requires print spool files to be written to disk, you can still build a secure workflow by automatically loading the generated PDF into memory, uploading it to your server, and deleting the temporary file right away.
This approach is reliable, easy to integrate, and widely used in document management, fax systems, workflow automation, and enterprise applications. It gives you complete control over what happens after every print job while letting users print as they normally do.