PDF-Converter 3.1

Description & documentation

The PDF-Converter is a local Windows tool that can convert over 115 different file formats losslessly into PDF documents. It uses a combination of proven, licence-free open-source components and integrated engines, and works either through a graphical interface with drag and drop or fully automated via the command line.

How it works

Depending on the file format, the program automatically chooses the best possible engine:

Engine	Task
PdfSharp + Ghostscript	Native PDF editing (merge, watermark, encryption, flattening, PDF/A)
Chromium (headless shell)	Renders HTML, MHT, Markdown and text pixel-perfect to PDF
MimeKit + MsgReader	Parses e-mails (.eml, .msg), extracts attachments, converts the text part
Markdig	Translates Markdown files into styled HTML (then Chromium)
Magick.NET (ImageMagick)	Converts any image format to the desired page size
Syncfusion (plugin)	Optional fast DLL engine for Word/Excel/PowerPoint – requires a licence
Microsoft Office	COM interop for Word/Excel/PowerPoint, if installed locally (optional)
LibreOffice	Reliable fallback for office and CAD formats

Engine order for Office formats

For Word, Excel and PowerPoint, the following order is tried:

1. Syncfusion (if enabled and DLLs present) – process-free, very fast
2. Microsoft Office (if usemsoffice=true and installed) – best layout fidelity
3. LibreOffice – indestructible fallback

If one engine fails, the next is automatically tried (except with password protection – that always ends immediately as a notice PDF).

Installation & requirements

Strictly required are the program itself (PdfConverter.exe) including the supplied files as well as the .NET 10 Runtime (Desktop Runtime, x64). The browser chrome-headless-shell is shipped in the folder chrome-headless-shell-win64/ next to the EXE and found automatically.

Optional, depending on your needs

Component	What for?	Source
LibreOffice	Office, spreadsheet, presentation and CAD formats	libreoffice.org
Microsoft Office	Alternative engine for .docx, .xlsx, .pptx	present locally
Syncfusion	Fastest engine for Word/Excel/PowerPoint (plugin)	your own Syncfusion licence
Ghostscript	Only for PDF/A conversion	ghostscript.com

Set up the Syncfusion plugin (optional)

The PDF-Converter can use the commercial Syncfusion library as an additional, very fast office engine – process-free and typically 10–20× faster than MS Office COM. The integration runs as a plugin via reflection: the Syncfusion DLLs are loaded at runtime, there is no build-time dependency, and the PDF-Converter itself remains distributable without a Syncfusion licence.

Requirements:

• Valid Syncfusion licence (Developer or Runtime) – end users without a licence simply leave the folder empty and continue to get MS Office / LibreOffice.
• Syncfusion Essential Studio (classic Base API, version 33.x or newer).

Setup:

1. Create a folder syncfusion/ next to PdfConverter.exe.
2. Copy the following 13 DLLs from C:\Program Files (x86)\Syncfusion\Essential Studio\Windows\<Version>\precompiledassemblies\net10.0\ into the folder:
   • Syncfusion.Licensing.dll
   • Syncfusion.Compression.Base.dll
   • Syncfusion.Pdf.Base.dll
   • Syncfusion.OfficeChart.Base.dll
   • Syncfusion.OfficeChartToImageConverter.Wpf.dll
   • Syncfusion.ExcelChartToImageConverter.Wpf.dll
   • Syncfusion.DocIO.Base.dll
   • Syncfusion.DocToPdfConverter.Base.dll
   • Syncfusion.XlsIO.Base.dll
   • Syncfusion.ExcelToPDFConverter.Base.dll
   • Syncfusion.Calculate.Base.dll
   • Syncfusion.Presentation.Base.dll
   • Syncfusion.PresentationToPdfConverter.Base.dll
3. In config.txt set:

   usesyncfusion = true
   syncfusion_license_key = YOUR_LICENSE_KEY_HERE

4. Restart the PDF-Converter – the log shows Syncfusion: N DLL(s) geladen, Lizenz registriert, Engine aktiv.

Without a licence key, the engine stays disabled (to avoid evaluation watermarks). If individual DLLs are missing, the loader writes that to the log and falls back cleanly to MS Office / LibreOffice.

Desktop version (graphical interface)

When started without arguments, the main window opens. The operation is deliberately kept simple.

Convert a single file

1. Drag the file to be converted onto the window by drag & drop – or select it via the … button next to "Source file".
2. The target file name is automatically suggested as <filename>.pdf in the same folder. It can be changed via the … button next to "Target file".
3. Set the desired PDF options (see below).
4. Click the Convert button.

Batch processing (several files)

Drag several files onto the window at once by drag & drop. The "Source file" field then shows [N files for batch conversion]. For each file the output is placed in the same folder as <filename>.pdf.

Merge mode (all files into one PDF)

If the Merge files (Merge) checkbox is enabled, all files in the batch are first converted individually and then merged into a single PDF. The target is then, e.g., Merged_Converted.pdf in the folder of the first source file.

Settings in the main window

Field	Description
PDF version	1.4 to 2.0 (default: 1.7)
PDF/A	No PDF/A, 1b, 2b or 3b (requires Ghostscript)
PDF flatten	Integrate annotations/form fields into the page
Use MS Office	If installed, prefers MS Office over LibreOffice
Watermark	Diagonal text on every page
PDF password	Password to open (user password)
Forbid printing	Print protection (automatically sets owner password)

The basic settings are loaded from config.txt and can be overridden in the window. The changes apply only to the current conversion and are not written back to the config.

Windows context menu (Explorer integration)

The PDF-Converter can add two entries to the right-click menu of the Windows Explorer:

• Right-click on a file → "Convert to PDF" – creates <filename>.pdf next to the original file. If the target name would collide with an already existing file (e.g. because the input itself is a PDF or because an earlier conversion has already created a <filename>.pdf), a counter is automatically appended: <filename> (1).pdf, <filename> (2).pdf etc. Originals are never overwritten.
• Right-click on a folder → "Convert into one PDF" – converts all supported files recursively in the folder (incl. subfolders) and merges them alphabetically sorted into a single PDF. The result is placed as <foldername>.pdf next to the folder.

Multiple file selection

If you select several files in Explorer and choose "Convert to PDF", all selected files are converted. Technically this is not trivial – with classic custom verbs, Windows starts the command only once with the first file by default. The PDF-Converter works around this internally via:

• Explorer COM query: the started process asks the active Explorer window via Shell.Application for all currently selected files.
• File-queue debouncer: if Windows does start several processes (depending on version/shell extension), a named-mutex-based master in %TEMP%\PdfConverter_BatchQueue.txt collects all incoming paths and processes them together.

Name-collision protection: if the target path would collide with an already existing file – either with one of the currently selected input files (e.g. with PDF-to-PDF) or with an older output from an earlier run – a counter is automatically appended (name (1).pdf, name (2).pdf etc.). Originals are never overwritten.

Setup via the graphical interface

In the main window, click Context menu ▾ at the top left and choose from the dropdown:

• Add – current user only (no admin rights needed, entry in HKCU)
• Add – all users (admin) (UAC prompt appears, entry in HKLM)
• Remove – current user / Remove – all users (admin)

For the "all users" variant, the PDF-Converter restarts itself elevated, writes the registry entries and exits; the GUI process gets the result reported back via exit code.

Note: if "all users" is chosen, the EXE should be located in a system-wide accessible path (e.g. C:\Program Files\…). If it sits under C:\Users\…, a warning appears, since other users may not be able to start this file.

Setup via the command line

PdfConverter.exe -installcontextmenu user      :: current user only (HKCU)
PdfConverter.exe -installcontextmenu machine   :: all users (HKLM, requires admin)
PdfConverter.exe -uninstallcontextmenu user
PdfConverter.exe -uninstallcontextmenu machine

The registry entries land under the keys …\Software\Classes\*\shell\PdfConverter.InPdfWandeln (file verb) and …\Software\Classes\Directory\shell\PdfConverter.InEinePdfWandeln (folder verb) – so the entry does not collide with other tools.

Command line (CLI)

If the EXE is called with at least one input and output file (or with -batch / -merge / -mergefolder), it runs without a graphical window (silent mode) and outputs the status on the console.

1. Convert a single file

PdfConverter.exe [input file] [output file] [options...]

Example:

PdfConverter.exe "C:\Dokumente\Rechnung.docx" "C:\PDFs\Rechnung.pdf" -watermark "Entwurf"

2. Batch processing (batch)

With -batch, all passed files are converted individually and placed as <filename>.pdf in the source folder. For PDF inputs (input and output would be identical), the conversion runs in place via a temp file that is atomically moved over the original at the end – this suits script pipelines that expect fixed output paths.

PdfConverter.exe -batch [file1] [file2] [file3] ...

Internal twin -contextbatch: identical to -batch, additionally enables the Explorer COM query, the file-queue debouncer and the name-collision protection. Used automatically by the Windows context-menu entry – in scripts, you should continue to use -batch so the tool does not accidentally read in the multiple selection of an open Explorer window.

3. Merge several files (merge)

With -merge, all files are first converted and then merged in the passed order into a single PDF.

PdfConverter.exe -merge [output.pdf] [input1] [input2] ...

Example:

PdfConverter.exe -merge "C:\Gesamt.pdf" "Deckblatt.docx" "Lebenslauf.md" "Zeugnis.heic"

4. Merge an entire folder (MergeFolder)

With -mergefolder, a folder is searched recursively (incl. all subfolders), all supported files are sorted alphabetically, converted and merged into a single PDF. The result is named <foldername>.pdf and is placed next to the passed folder. If the file already exists, a counter is appended (foldername (1).pdf). This mode is also used by the Windows context-menu entry for folders.

PdfConverter.exe -mergefolder [folder path]

Example:

PdfConverter.exe -mergefolder "C:\Projekt\Dokumentation"

5. Add/remove the Windows context menu

PdfConverter.exe -installcontextmenu [user|machine]
PdfConverter.exe -uninstallcontextmenu [user|machine]

For details, see the Windows context menu section above.

CLI options

Option	Values	Description
-watermark	"Text"	Places a 45-degree watermark across every page
-userpassword	"Password"	The finished PDF requires this password to open
-ownerpassword	"Password"	Restricts changes, requires this password
-forbidprinting	true / false	Blocks printing (automatically sets owner password)
-flatten	true / false	Reduces the PDF to a purely passive image layer
-pdfa	1b, 2b, 3b	Converts to the long-term archive format via Ghostscript
-usemsoffice	true / false	Forces MS Office instead of LibreOffice
-writelog	true / false	Writes logs to log.txt next to the EXE
-skippdftopdf	true / false	PDF input is copied directly instead of re-converted

Return values: 0 = success, 1 = at least one error.

Configuration file config.txt

The file config.txt sits next to PdfConverter.exe and is read on every start. CLI parameters override the values in the config. Empty lines and lines starting with # are comments.

General

Key	Values	Default	Description
writelog	true/false	false	Write logs to log.txt
lokalekopie	true/false	false	Additionally place successful PDFs in ./lokalekopie/
skippdftopdf	true/false	false	In CLI mode, do not re-convert PDF inputs but copy them

PDF output

Key	Values	Default	Description
pdfversion	1.4 … 2.0	1.7	PDF version of the result
pdfa	none, 1b, 2b, 3b	none	PDF/A conformance (requires Ghostscript)
flatten	true/false	true	Integrate form fields into the page
watermark	Text	empty	Diagonal watermark
userpassword	Password	empty	Password to open
ownerpassword	Password	empty	Password for changes
forbidprinting	true/false	false	Print protection active

Office engine

Key	Values	Default	Description
usesyncfusion	true/false	false	Enable the Syncfusion plugin engine (requires DLLs + licence)
syncfusion_license_key	Text	empty	Syncfusion runtime licence key (case-sensitive)
usemsoffice	true/false	true	Use MS Office (if installed)
bei_msoffice_fehler_libreoffice_verwenden	true/false	true	On a general MS Office error, try LibreOffice
timeoutfehler_umgehen	true/false	false	On timeout, additionally try LibreOffice

Office automation (only if usemsoffice=true)

Key	Values	Default	Description
office_allow_macros	true/false	true	true = macros allowed (Trust Center decides), false = macros completely disabled
office_update_external_links	true/false	true	true = linked logos/data sources are reloaded, false = prevents hangs with unreachable sources

Timeout (for office conversion, MS Office & LibreOffice)

Key	Values	Default	Description
timeout_base_seconds	Number	60	Base timeout in seconds
timeout_seconds_per_mb	Number	15	Additional seconds per MB of file size

Formula: timeout = timeout_base_seconds + timeout_seconds_per_mb × file-size-MB
With 120 + 30: 5 MB → 270 s (4.5 min), 23 MB → 810 s (13.5 min).

Chrome/Edge (for HTML, Markdown, text, e-mail)

Key	Values	Default	Description
chrome_path	Path	empty	Optional: alternative browser path

Search order when chrome_path is empty: supplied chrome-headless-shell-win64/ next to the EXE → chrome-win64/chrome.exe → chromium/chrome.exe → system Edge → system Chrome.

Example configuration

# Basis
writelog = true
usemsoffice = true
pdfversion = 1.7
flatten = true

# Office-Automation
office_allow_macros = true
office_update_external_links = true

# Timeout für große Excel-Dateien
timeout_base_seconds = 120
timeout_seconds_per_mb = 30

# Optional: Wasserzeichen & Security
# watermark = ENTWURF
# userpassword = gast
# forbidprinting = false

Supported file formats (115+)

Text, code & Markdown (via Markdig / Chromium)
.txt, .xml, .ini, .log, .json, .md, .markdown, .cs, .cpp, .c, .h, .java, .py, .js, .css, .sql, .sh, .bat, .ps1, .yaml, .yml

Images & vectors (via Magick.NET)
.jpg, .jpeg, .png, .gif, .bmp, .tif, .tiff, .heic, .heif, .webp, .psd, .raw, .cr2, .nef, .orf, .sr2, .eps, .tga, .pcx, .jp2, .j2k, .ico, .wmf, .emf, .svg

Word / text documents (via Syncfusion, MS Office or LibreOffice)
.doc, .docx, .docm, .dot, .dotx, .dotm, .rtf, .odt, .sxw, .wpd, .wps, .wri, .fodt, .epub, .lwp, .cwk, .pages

Excel / spreadsheets (via Syncfusion, MS Office or LibreOffice)
.xls, .xlsx, .xlsm, .xlsb, .xlt, .xltx, .xltm, .csv, .tsv, .vif, .viv, .123, .dbf, .dif, .slk, .fods, .ods, .sxc, .numbers, .wk1, .wk3, .wk4, .wq1, .wq2

PowerPoint / presentations (via Syncfusion, MS Office or LibreOffice)
.ppt, .pptx, .pptm, .pot, .potx, .potm, .pps, .ppsx, .ppsm, .odp, .sxi, .fodp, .key

Drawings, layouts & CAD (via LibreOffice Draw)
.odg, .vsd, .vsdx, .pub, .cdr, .dxf, .dwg

Web & e-mail (via Chromium & MimeKit)
.html, .htm, .mht, .eml, .msg

PDF (via PdfSharp)
.pdf – also as a PDF package (portfolio): it is automatically unpacked, every sub-file converted and merged chronologically into one PDF.

Unknown extensions with text content (via text fallback)
Files with unusual extensions (e.g. .conf, .env, scripts without an extension, log files with an exotic extension) are checked heuristically: BOM check, null-byte check and proportion of non-printable characters. If they appear textual, they land in the text-to-PDF path and are rendered as code/text. Real binary files (.exe, .dll, archives, media etc.) continue to be answered with the error notice PDF.

Error handling

If a file cannot be converted, the program does not abort, but creates a notice PDF at the expected target path. This keeps job processing stable in pipelines.

Situation	Notice PDF contains
Source file is password-protected	"The file could not be converted to PDF because it is protected with a password."
Timeout (conversion took too long)	"Error converting to PDF. (Timeout)"
General error	"The file could not be converted to PDF due to an error." + error message as detail

Password detection: recognises both user passwords (password to open) and owner passwords (print/copy protection). The check runs via PdfReader.Open(..., Modify) before the actual conversion flow and also takes effect in skip mode (skippdftopdf = true), so encrypted PDFs do not slip through into the pipeline unnoticed.

Logging: with writelog = true (or -writelog true), all steps are written to the file log.txt in the current working directory, including timestamps, engine selection, timeout values and any error stack traces. With parallel instances (e.g. multiple context-menu calls), the logger synchronises via retry loops so that no lines are lost.

Grep anchors for script evaluation

Anchor	Meaning
Datei ist passwortgeschuetzt	An input file was encrypted
Hinweis-PDF erzeugt:	Target path contains a placeholder PDF
Konvertierungs-Timeout bei Datei:	Timeout case
Allgemeiner Konvertierungsfehler bei Datei:	Other error

Licence & components

The PDF-Converter itself is available under the MIT licence and can be freely distributed. Components used:

• PdfSharp 6 (MIT) – PDF manipulation
• PuppeteerSharp (MIT) – Chromium control
• MimeKit (MIT) – e-mail parsing
• MsgReader (MIT) – .msg parsing
• Magick.NET (Apache 2.0) – image conversion
• Markdig (MIT) – Markdown rendering
• LibreOffice (MPL/LGPL) – external office conversion
• Ghostscript (AGPL) – external PDF/A converter

Optional Syncfusion plugin (commercial licence): loaded at runtime via reflection – there is no build-time dependency on Syncfusion. The DLLs are provided by the user only when needed, with their own licence, so that the PDF-Converter can still be passed on without a Syncfusion licence.

System requirements

• Microsoft Windows (x64)
• .NET 10 Runtime (Desktop Runtime)
• Supplied chrome-headless-shell (in the folder chrome-headless-shell-win64/)
• Optional: LibreOffice, Microsoft Office, Ghostscript, Syncfusion

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