PDFCreator is an application for converting documents into Portable Document Format (PDF) format on Microsoft Windows  operating systems. It works by creating a virtual printer that prints to PDF files, and thereby allows practically any application to create PDF files by choosing to print from within the application and then printing to the PDFCreator printer.

Implementation
The application is GPL-licensed free software, written in Microsoft Visual Basic. It works with 64-bit and 32-bit Windows versions including Windows 7, internally using mostly 32-bit code. The actual PDF generation is handled by Ghostscript.
Besides being installed as a virtual printer, PDFCreator can be associated with .ps files to manually convert PostScript to PDF format.
PDFCreator can convert to the following file formats: PDF (including PDF/A (1b) and PDF/X (X-3:2002, X-3:2003 and X-4), PNG, JPEG, BMP, PCX, TIFF, PS, EPS, TXT, PSD, PCL, RAW. It also allows to digitally sign PDF documents.
Since version 0.8.1 RC9 (2005) PDFCreator supports access to its functionality via an ActiveX/COM interface; this allows programs written in other languages, like C#, Delphi, Visual Basic, .NET, VBA, Perl, Python, Ruby, WinBatch, Windows Scripting Host (JScript, VBScript), to utilise and control PDFCreator programatically.
The installation package includes a closed-source browser toolbar that is considered by many users to be malicious software (see below). Although technically an optional component, the opt-out procedure is a multi-step process which is considered by many to be intentionally confusing. In addition to the spyware activity described below, the toolbar allows one-click creation PDFs from the current webpage and includes a search tool.
PDFCreator allows the user to disable printing, copying of text or images and modifying the original document. The user can also choose between two types of passwords, user and owner, to restrict PDF files in several ways. The former is required to open the PDF file, while the latter is necessary in order to change permissions and password. Encryption can be either 40 bits, compatible with Adobe Acrobat 3.0 or 4.0, or 128 bits for Acrobat 5.0 or higher.
Starting with version 0.9.6, there is full support for Windows Vista and version 0.9.7 provides support for Windows 7.

• Inclusion of malware

Starting with version 0.9.7 (February 2009), PDFCreator has included a new toolbar application that is considered by many to be malicious software . The end-user-license agreement for Pdfforge Toolbar by Spigot, Inc. (versions prior to 0.9.7 have a different, optional toolbar called "PDFCreator Toolbar"), states that the software will:
modify your Microsoft Internet Explorer and/or Mozilla Firefox browser settings for the default search engine, address bar search, "DNS error" page, "404 error" page, and new tab page to facilitate more informative responses as determined by The Toolbar
The software has generated considerable controversy among PDFCreator users for the following reasons:

1. The opt-out procedure during installation is confusing. There are two separate screens where the user must take action if they do not wish to install the toolbar, one of which is not clearly labeled. This confusing process leads many users to believe they have opted-out of the installation when they have not. Some users erroneously report that it is not possible to opt-out of the toolbar installation, which is not true. If one reads the instructions carefully and follows them, it IS possible to install PDFCreator without also installing the unwanted toolbar, even if the process is confusing.
2. The software performs "browser-hijacking". The toolbar reports your browsing-habits to an advertising network and inserts unwanted advertising content into new-browser-windows and error-pages.
3. Uninstalling the toolbar does not revert changes to browser settings: Homepage, search-provider, and other browser settings modified by the toolbar are not reverted on uninstallation, making removal frustrating and difficult. This in combination with the confusing opt-out procedure during installation leads to considerable ill-will from users who often feel "duped".

• Response from SourceForge

SourceForge, who hosts the downloads for PDFForge and many other projects, has received criticism for failing to adequately respond to complaints about the confusing toolbar installation process. Writing in May 2009 Steven Avery stated:
PDFCreator, formerly a respected open source product, is causing havoc with a malware install toolbar. Amazingly SourceForge hasn't done anything about this yet and still lists the software, and for many their trust level is shaken as well.
In June 2009, SourceForge marked the report as Invalid.[12] No action was taken to remove or fix the problems described.

• Response from PDFForge

PDFForge, which created PDFCreator, has a FAQ regarding the toolbar spyware[13] that states:
Is this spyware then?
I think the main difference is if this is done unasked and undisclosed amount.
(..) Furthermore, the company works together with major Anti Ad- and Spyware companies to ensure, that it can be consider transparent und unharmful for the user. These unclude: Microsoft Windows , Anti-Spyware Webroot SpySweeper, Computer Associates Pest Patrol, PC Tools Spyware Doctor, Aluria Spyware Scanner and Spyware Eliminator.

• Response from A/V Vendors

Many Anti-Virus vendors have classified the software as not-harmful due to what they consider to be adequate disclosure in the installation process and EULA for the toolbar, although Sophos has continued to classify the toolbar as Spyware against protests from PDFForge.