🟢 Beginner–Intermediate ⚙️ Type: PDF Editor / API / Local Server 💸 Free & Open Source ⭐ 83,000+ GitHub Stars
What is Stirling-PDF?
Stirling-PDF is the undisputed heavyweight champion of open-source PDF tools. Originally launched as a simple, locally-hosted Docker container for homelabbers, it has exploded into a massive, enterprise-grade platform boasting over 30 million downloads and 83,000+ GitHub stars. It is widely considered the ultimate free replacement for Adobe Acrobat.
In its massive 2026 V2 release, Stirling-PDF completely transformed. It is no longer just a web application. It now ships as a lightning-fast native Desktop app for macOS and Windows, featuring full offline support and “Open With” file integration. Under the hood, it packs over 60 different PDF operations powered by battle-tested libraries like PDFBox, LibreOffice, and Tesseract OCR.
Most recently (as of version 2.13), the platform has leaned heavily into AI. Stirling-PDF now includes an embedded AI assistant and native Model Context Protocol (MCP) support. This means you can point AI coding agents like Cursor or Claude Desktop directly at your local Stirling instance, allowing the AI to read, extract, and automate complex PDF pipelines securely on your machine without uploading sensitive documents to a third-party cloud.
Who is it for?
- Everyday Users who are sick of expensive monthly subscriptions just to merge, sign, or compress a PDF document.
- Enterprise IT & Healthcare Professionals working with highly sensitive files (medical records, legal documents, financial reports) who legally cannot upload documents to random “free PDF editor” websites.
- Homelabbers & DevOps who want to run a private, self-hosted document processing API inside their own secure network via Docker or Kubernetes.
- AI Developers looking for a robust, local backend to extract text, tables, and OCR data for Retrieval-Augmented Generation (RAG) pipelines without paying per-page API fees.
What makes it special?
- Absolute Privacy — Whether you use the native desktop app or host the Docker container locally, your files never leave your machine. The V2 web client uses stateful processing (IndexedDB) to keep files local until you are ready to export.
- 60+ Built-in Tools — It can do virtually everything: merge, split, rotate, compress, redact text, password protect, add watermarks, convert to/from Word/Excel/HTML, and perform full-page OCR.
- Automation Pipelines — You do not have to process files manually. You can set up visual pipelines to automatically sort, encrypt, and route thousands of documents simultaneously.
- The MCP Integration — The new Model Context Protocol endpoints mean your local AI tools can seamlessly ask Stirling-PDF to extract text from a scanned document or convert a PDF to Markdown programmatically.
Requirements before you start
Stirling-PDF offers incredibly flexible deployment options based on your technical comfort level:
- For Desktop Users: Any modern Windows, macOS, or Linux machine. No internet required after downloading the installer.
- For Self-Hosters: A server or NAS running Docker and Docker Compose. At least 2GB of RAM is recommended if you plan on running heavy OCR tasks or LibreOffice conversions.
- For Developers: Java 21+ if you prefer to run the raw
.jarfile on bare metal.
Step-by-step installation
Choose the installation method that best fits your workflow.
Method 1 — Native Desktop App (Easiest)
If you just want a standard application to replace Adobe Acrobat on your personal computer:
- Go to stirling.com/download.
- Download the
.exefor Windows or the.dmgfor Mac. - Install it like a normal application. You can now set it as your default PDF viewer in your OS settings!
Method 2 — Docker Compose (For Homelabs & Servers)
If you want to run the web UI on a home server (like Proxmox or a Synology NAS) so anyone on your Wi-Fi can access it:
- Create a
docker-compose.ymlfile on your server and paste the following:
services:
stirling-pdf:
image: frooodle/s-pdf:latest
ports:
- '8080:8080'
volumes:
- ./trainingData:/usr/share/tessdata # For OCR language packs
- ./extraConfigs:/configs
- ./customFiles:/customFiles/
environment:
- DOCKER_ENABLE_SECURITY=false
- INSTALL_BOOK_AND_ADVANCED_HTML_OPS=false- Run
docker compose up -din your terminal. - Open your browser and navigate to
http://localhost:8080to access the full suite!
Method 3 — Enabling MCP for AI Agents
If you are using Stirling-PDF version 2.13+ via Docker or Desktop, the MCP endpoints are available out of the box. You can connect your local Claude Desktop or Cursor instance by pointing their configuration files to Stirling’s local API port, granting your AI agents read/write access to your local document processing queue.
Common errors and fixes
| Error | What it means | How to fix it |
|---|---|---|
| PDF to Word/Excel conversion fails or is missing | You are using the standard or “ultra-lite” Docker image, which does not include the massive LibreOffice backend required for complex Office format conversions. | Update your Docker image tag from :latest to :latest-fat. This will download a much larger container that includes all necessary fonts and the LibreOffice suite. |
| OCR is failing or ignoring non-English text | The Tesseract OCR engine only ships with English by default to save space. | You need to download the specific Tesseract .traineddata files for your desired languages and place them in the mapped /usr/share/tessdata Docker volume. |
| High RAM usage or container crashing during batch merge | Processing massive PDFs (1,000+ pages) in parallel can easily overwhelm the JVM memory allocation within the Docker container. | Limit the memory of the container via Docker settings, or process smaller batches. Version 2.12 significantly improved Java memory management, so ensure you are running the latest release. |
Free vs Paid comparison
| Feature | Stirling-PDF (Open Source / Desktop) | Stirling Processor (Enterprise API) |
|---|---|---|
| Cost | $0 (Free forever) | Pay-As-You-Go ($0.05 per doc) or Custom SLA |
| Core PDF Tools (Split, Merge, OCR) | 🟢 Unlimited | 🟢 Unlimited |
| Hosting Requirements | ⚠️ Requires your own desktop or server hardware | ✅ Fully managed cloud API scaling to millions of docs |
| Org-Wide Compliance & SSO | ❌ Basic auth only | ✅ Included (SAML, Okta, auditing rules) |
Bottom line: There is absolutely no reason to pay for a personal Adobe Acrobat subscription anymore. Stirling-PDF has evolved from a niche Docker project into a highly polished, desktop-native powerhouse. With 60+ tools running entirely offline and new AI/MCP integrations that prepare it for the agentic future, it is an essential install for any developer, student, or privacy-conscious professional.
Alternatives — 3 similar tools
1. PDF X-Change Editor
Often considered the best proprietary, native PDF editor for Windows. While its interface looks a bit dated, it is incredibly fast and feature-rich. Unlike Stirling-PDF, it is closed-source and not free for advanced editing features, but it has a massively loyal following among Windows power users for its smooth text rendering and deep customization.
2. BentoPDF
A much newer, incredibly lightweight open-source alternative favored by some homelabbers. While Stirling-PDF has grown into a massive enterprise platform with a large footprint, BentoPDF intentionally strips away the “bloat” and focuses on doing a few core PDF manipulations extremely fast with minimal server resources.
3. Adobe Acrobat Pro
The industry standard that started it all. If you work in graphic design and need perfectly integrated color-management, pre-flight tools for commercial printing, or seamless integration with Adobe Illustrator, Acrobat remains the king. However, its heavy subscription cost and forced cloud integration make it overkill for 95% of standard business tasks.
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