Stirling PDF — Self-Hosted PDF Editor & Toolkit

What Stirling PDF Does

50+ PDF operations organized by category:

Page Operations

• Merge multiple PDFs into one
• Split PDF by pages, size, or bookmarks
• Rotate, reorder, and remove pages
• Extract specific page ranges
• Add page numbers

Conversion

• PDF ↔ Image (PNG, JPEG, TIFF, WebP)
• PDF → Word (DOCX), Excel, PowerPoint
• HTML → PDF, Markdown → PDF
• PDF ↔ PDFA (archival format)

Security

• Add/remove password protection
• Add digital signatures
• Redact sensitive content
• Add watermarks (text or image)
• Set permissions (print, copy, edit)

Document Processing

• OCR (extract text from scanned PDFs)
• Compress PDF file size
• Flatten forms
• Extract images from PDF
• Add/edit metadata

Advanced

• Compare two PDFs visually
• Auto-rename based on content
• Multi-page layout (2-up, booklet)
• Repair corrupted PDFs

Self-Hosting

Docker (Simple)

docker run -d --name stirling-pdf 
  -p 8080:8080 
  -v ./training-data:/usr/share/tessdata 
  -v ./configs:/configs 
  -e DOCKER_ENABLE_SECURITY=false 
  frooodle/s-pdf:latest

Docker Compose (with OCR languages)

services:
  stirling-pdf:
    image: frooodle/s-pdf:latest
    ports:
      - "8080:8080"
    volumes:
      - ./training-data:/usr/share/tessdata
      - ./configs:/configs
      - ./logs:/logs
    environment:
      DOCKER_ENABLE_SECURITY: "false"
      INSTALL_BOOK_AND_ADVANCED_HTML_OPS: "true"
      LANGS: "zh_sim,zh_tra,eng,jpn,kor"  # OCR languages
    restart: unless-stopped

Full Version (with LibreOffice)

# Full version includes Word/Excel/PPT conversion
docker run -d frooodle/s-pdf:latest-fat

Key Features

API Access

Every operation is available via REST API:

# Merge PDFs
curl -X POST http://localhost:8080/api/v1/general/merge-pdfs 
  -F "fileInput=@file1.pdf" 
  -F "fileInput=@file2.pdf" 
  -o merged.pdf

# Convert PDF to images
curl -X POST http://localhost:8080/api/v1/convert/pdf/img 
  -F "fileInput=@document.pdf" 
  -F "imageFormat=png" 
  -F "dpi=300" 
  -o images.zip

# OCR a scanned PDF
curl -X POST http://localhost:8080/api/v1/misc/ocr-pdf 
  -F "fileInput=@scanned.pdf" 
  -F "languages=chi_sim+eng" 
  -o ocr-result.pdf

# Compress PDF
curl -X POST http://localhost:8080/api/v1/general/optimize-pdf 
  -F "fileInput=@large.pdf" 
  -F "optimizeLevel=3" 
  -o compressed.pdf

Multi-Language OCR

Stirling PDF uses Tesseract OCR with support for 100+ languages:

Pipeline Operations

Chain multiple operations together:

Input PDF → OCR → Compress → Add Watermark → Password Protect → Output

Why Self-Host PDF Tools?

Cloud PDF tools (iLovePDF, SmallPDF, etc.):
✗ Your documents uploaded to third-party servers
✗ File size limits on free tier
✗ Monthly subscription for full features
✗ Privacy concerns for sensitive documents

Stirling PDF:
✓ Documents never leave your server
✓ No file size limits
✓ All features free, forever
✓ Perfect for sensitive/legal/medical documents

FAQ

Q: Does Stirling PDF support Chinese OCR? A: Yes. Configure chi_sim (Simplified Chinese) or chi_tra (Traditional Chinese) via the LANGS environment variable. Language packs download automatically on first use.

Q: What's the difference between the standard and "fat" images? A: The standard image includes basic PDF operations. The fat image additionally bundles LibreOffice, enabling PDF ↔ Word/Excel/PPT conversion. Fat image is about 1.5GB; standard is about 400MB.

Q: Any file size limits? A: The self-hosted version has no file size limit. Processing speed depends on server resources. For large-file OCR, allocate at least 2GB RAM.