Stirling PDF

1. What is Stirling PDF?

Stirling PDF is a free, open-source PDF toolbox that gathers more than 50 common PDF jobs in one place: merge several files into one, split pages, compress to reduce size, rotate pages, convert between PDF and Word or images, recognise text in scans (OCR), add passwords, sign documents, and redact sensitive information. It can replace paid online PDF services such as iLovePDF or Smallpdf, with one important difference: when you install it on your computer, your files are processed locally instead of being uploaded to someone else's server.

There are two ways to use it: install it as a desktop application (like any normal program), or run it as a web server so several people can share it. The interface is available in more than 40 languages.

A good fit if:

• You often merge, split, compress or convert PDF files and would rather not upload documents to the web.
• You want software that works offline for basic tasks.
• You need a free tool for yourself or a small team.

Not the right fit if:

• You only need to read PDFs (your browser or built-in viewer already does that).
• You want to remove an existing watermark: Stirling PDF can add watermarks but has no tool to strip them out.

2. What you need

The easiest path for a beginner is the desktop app, so the notes below focus on that.

• A computer running Windows, macOS (Apple Silicon or Intel), or Linux. The official docs do not list exact OS versions or disk space; check https://docs.stirlingpdf.com if unsure.
• No account and no API key are required, and manual PDF tools are free.
• On Windows, the desktop app draws its interface with the "Microsoft Edge WebView2 Runtime" (a Windows component, usually already present on Windows 11). If the app opens with no visible window, install it from the official page: https://developer.microsoft.com/en-us/microsoft-edge/webview2/

If you prefer to run it as a web server instead of installing the app, you will need one of the following (only choose this if you really need it):

• Docker: software that packages an app to run in its own isolated box, available at https://www.docker.com/
• Java JDK 25 (Temurin 25): the runtime for the .jar version, available at https://adoptium.net/

3. Step-by-step installation

Step 1: Install the app on Windows

Go to the official download page and get the Windows installer at https://files.stirlingpdf.com/win-installer.exe. Run the downloaded file and follow the setup steps (it installs to C:\Program Files\Stirling-PDF by default). When it finishes, type "Stirling PDF" in the Start menu to open it.

If you are comfortable with the command line, you can install it with winget in PowerShell:

winget install StirlingTools.StirlingPDF

What you should see: a Stirling PDF window with a list of tools on the left and a drag-and-drop area in the middle, with no login prompt.

Step 2: Install the app on macOS

Download the installer at https://files.stirlingpdf.com/mac-installer.dmg (it runs natively on both Apple Silicon and Intel Macs). Open the .dmg file, drag Stirling PDF into your Applications folder, then launch it.

If macOS blocks it because it cannot verify the developer, go to System Settings → Privacy & Security, scroll to the Security section, click "Open Anyway" next to the Stirling PDF message, then launch it again.

Step 3: Install the app on Linux

Pick the package that matches your distribution:

# Ubuntu / Debian
wget https://files.stirlingpdf.com/linux-installer.deb
sudo dpkg -i linux-installer.deb

# Fedora / RHEL
wget https://files.stirlingpdf.com/linux-installer.rpm
sudo dnf install ./linux-installer.rpm

With the AppImage there is nothing to install; just download it, make it executable and run (on Ubuntu 22.04 or newer the docs say you first need sudo apt-get install libfuse2):

wget https://files.stirlingpdf.com/linux-installer.AppImage
chmod +x linux-installer.AppImage
./linux-installer.AppImage

Step 4 (advanced): Run it as a web server with Docker

This is for people who want to use it through a browser or share it on a local network. After installing Docker, open a command window and run:

docker run -d --name stirling-pdf -p 8080:8080 -v ./stirling-data:/configs docker.stirlingpdf.com/stirlingtools/stirling-pdf:latest

Then open http://localhost:8080 in a browser.

Note: The Docker version has login enabled by default, with a first account of admin / stirling. Change the password right after your first login. If you use it alone and want to turn login off, add -e SECURITY_ENABLELOGIN=false to the command above.

Step 5 (advanced): Run the JAR version

If you have a server with Java JDK 25 installed, download one of the .jar files from the official page, for example the login-enabled build at https://files.stirlingpdf.com/Stirling-PDF-with-login.jar, then run:

java -jar Stirling-PDF-with-login.jar

Open http://localhost:8080 to use it.

4. First run

A concrete example: merge two PDF files into one.

Step 1: Switch the interface to your language (optional)

Open Settings or click the globe icon and pick your language.

Step 2: Choose the tool

Type merge in the "Search tools…" box, or pick Merge from the list on the left.

Step 3: Add files and run

Click "Add Files" or drag two PDF files into the middle of the screen. Reorder them if needed, then click the run button. Wait a few seconds and download the result.

What you should see: a new PDF that combines both documents, saved to the folder you chose.

The table below helps you find the right tool quickly:

What you want to do	Tool in the app
Merge several PDFs	Merge
Reduce file size	Compress
Sign a document	Sign
Recognise text in a scan	OCR
Hide ID or account numbers	Redact
Split or rotate pages	Split, Rotate
Add a password	Add Password
Convert Word/images to and from PDF	Convert

5. Common problems and fixes

• Windows: the app runs in Task Manager but no window appears. Cause: the Microsoft Edge WebView2 Runtime is missing. Fix: install it from https://developer.microsoft.com/en-us/microsoft-edge/webview2/ and reopen the app.
• macOS blocks the app. Cause: the system does not yet trust an app downloaded outside the App Store. Fix: go to System Settings → Privacy & Security → click "Open Anyway", then reopen it.
• The Docker version asks for a login. Cause: login is on by default. Fix: sign in with admin / stirling and change the password, or restart with -e SECURITY_ENABLELOGIN=false.
• Port 8080 is already in use (Docker errors on startup). Fix: change the host port, for example -p 8081:8080, then open http://localhost:8081.
• Low-spec machine, the Docker version feels heavy. Fix: use the light image docker.stirlingpdf.com/stirlingtools/stirling-pdf:latest-ultra-lite. Conversely, if fonts or conversion tools are missing, use the image latest-fat (the docs describe it as including extra fonts and tools).
• The JAR version reports missing tools during OCR or conversion. Cause: some features need extra background software (LibreOffice, Tesseract OCR, QPDF). The official docs list LibreOffice and Tesseract OCR among the extra software needed for the server (JAR) version; see the installation page at https://docs.stirlingpdf.com for the full list.

6. Uninstalling and updating

• Update the desktop app: it checks for new versions itself. Go to Settings → Software Updates to check and choose how updates are applied. If you installed via winget: winget upgrade StirlingTools.StirlingPDF; via Homebrew on Mac: brew upgrade --cask stirling-pdf.
• Update the Docker version: stop and remove the old container, pull the new image, then run it again:

docker stop stirling-pdf
docker rm stirling-pdf
docker pull docker.stirlingpdf.com/stirlingtools/stirling-pdf:latest

Then rerun the command from Step 4 (data in the stirling-data folder is kept).

• Uninstall the desktop app: on Windows go to Settings → Apps → Installed apps, find Stirling PDF and remove it; on macOS drag Stirling PDF from Applications to the Trash.

7. Frequently asked questions

• Does it cost anything? No. The self-hosted version is free, and the Free plan covers up to 5 users and every PDF tool. Paid Team/Enterprise plans exist for large organisations, but you are not required to use them.
• Do I need an internet connection? The desktop app does basic tasks (merge, split, rotate, sign) locally with no internet. Some advanced features (OCR, Office conversions) may need a server or extra installed components.
• Are my files sent anywhere? In the desktop app's default local mode, files are processed on your machine and are not sent to any server on their own. The README says you can work with PDFs "without sending documents to external services".
• Will it run on a weak machine? Yes. Use the desktop app or the latest-ultra-lite Docker image for low-spec hardware.
• What is the latest version? At the time of writing, the latest release is v3.0.1 (26 September 2026). Check the official Releases page for the current one: https://github.com/Stirling-Tools/Stirling-PDF/releases