# PDFCheck - Full Technical Documentation

## Overview

PDFCheck (https://pdfcheck.online) is a privacy-focused PDF platform for analysis, validation, conversion, editing, and AI-assisted document review. Current account allowances and plan limits are documented on the pricing and API documentation pages.

## Core Tools

### 1. PDF Metadata Checker
**URL**: https://pdfcheck.online/

Extracts and analyzes standard and custom PDF metadata fields:
- **Creation & Modification Dates**: Verifies if internal timestamps match claimed timeline
- **Software Identification**: Detects specific software (Producer/Creator) used to generate the PDF
- **Author Information**: Extracts author names and contributor details
- **PDF Version**: Identifies PDF specification version (1.4, 1.7, 2.0)
- **Edit History**: Detects incremental updates and modifications
- **File Structure**: Analyzes linearization, page count, and layout

### 2. PDF Validator
**URL**: https://pdfcheck.online/pdf-validator

Validates PDF structure and integrity:
- **Corruption Detection**: Identifies damaged or malformed PDFs
- **Structure Validation**: Verifies PDF specification compliance
- **PDF/A Compliance**: Checks archival format standards
- **Reference Integrity**: Validates cross-references and object streams

### 3. AI Content Detector
**URL**: https://pdfcheck.online/pdf-ai-detection

Detects AI-generated PDF signatures:
- **LLM Tool Detection**: Identifies PDFs created by ChatGPT, Claude, and other AI systems
- **Software Fingerprinting**: Detects ReportLab, PyPDF, WeasyPrint, pdf-lib, PDFKit, Puppeteer
- **Pattern Recognition**: Analyzes metadata patterns typical of AI generation
- **Confidence Scoring**: Provides likelihood assessment of AI involvement

### 4. AI PDF Chat
**URL**: https://pdfcheck.online/pdf-ai-chat

Chat with a PDF through PDFCheck-provided AI providers:
- **Account-Gated Uploads**: Guests can view the page, but uploading requires a free account
- **Monthly Allowance**: Free accounts include 1 PDF and 3 successful AI messages per calendar month
- **Premium Allowance**: Pro and Business include 1000 successful AI messages per month and unlimited one-PDF chat sessions
- **Local Retrieval**: PDFCheck extracts page text into private source chunks and sends only relevant excerpts to OpenAI or DeepSeek
- **Grounded Answers**: Answers include validated page citations from the uploaded PDF
- **PDF Review Workspace**: Shows the PDF preview beside chat, extracted source chunks, selected context, comments, and AI-generated document notes
- **OCR Fallback**: If normal extraction finds no text, PDFCheck can render PDF pages as JPG images and send them to the configured OpenAI OCR model
- **Markdown Export**: Users can download extracted content and annotations as Markdown
- **Review Prompts**: Summaries, important sections, grammar issues, internal consistency, key dates/numbers, risks, and simple explanations
- **Retention**: Original PDFs are stored privately until the user deletes the chat

### 5. PDF Optimizer
**URL**: https://pdfcheck.online/optimize-pdf

Compresses and reduces PDF file size:
- **Screen (72dpi)**: Maximum compression for web viewing
- **eBook (150dpi)**: Balanced quality and size
- **Printer (300dpi)**: Minimal compression for printing
- **Prepress (300dpi)**: High quality for professional printing

### 6. PDF Signature Checker
**URL**: https://pdfcheck.online/pdf-signature-checker

Verifies digital signatures and certificates in PDF documents:
- **Signature Detection**: Identifies all digital signatures in a PDF
- **Certificate Analysis**: Extracts signer name, organization, and certificate details
- **Integrity Verification**: Checks if the document has been modified after signing
- **Timestamp Validation**: Verifies signing timestamps and certificate validity
- **Trust Chain**: Analyzes certificate authority and trust chain

### 7. PDF Image Extractor
**URL**: https://pdfcheck.online/extract-images

Extracts all images from PDF documents:
- **Full Extraction**: Extracts every embedded image from all pages
- **Original Quality**: Preserves original image resolution and format
- **Batch Download**: Download all extracted images as a ZIP archive
- **Format Support**: Handles JPEG, PNG, TIFF, and other embedded image formats
- **Preview Gallery**: Visual preview of all extracted images before download

### 8. PDF Accessibility Checker
**URL**: https://pdfcheck.online/pdf-accessibility-checker

Checks PDF accessibility compliance and structure:
- **Tagged PDF Detection**: Verifies if the PDF has proper tag structure for screen readers
- **Document Title**: Checks for a meaningful document title in metadata
- **Language Declaration**: Validates that the document language is specified
- **Text Content**: Confirms the PDF contains extractable text (not image-only)
- **Bookmarks/Navigation**: Checks for document outline and navigation aids
- **Accessibility Score**: Provides an overall score (0-5) with actionable recommendations

### 9. PDF Form Filler
**URL**: https://pdfcheck.online/fill-pdf-form

Fill in interactive PDF form fields online. Upload a PDF with form fields, fill them in via the browser, and download the completed document.

### 10. PDF Form Builder
**URL**: https://pdfcheck.online/build-pdf-form

Add fillable form fields (text inputs, checkboxes, dropdowns) to any PDF document. Upload a PDF, visually place form fields, and export as an interactive fillable PDF.

### 11. PDF Editor
**URL**: https://pdfcheck.online/edit-pdf

Edit PDF text, images, and annotations online. Upload a PDF, make edits directly in the browser, and download the modified document.

### 12. PDF Highlighter
**URL**: https://pdfcheck.online/highlight-pdf

Highlight and annotate PDF files online. Upload a PDF, draw transparent highlights, add text notes or rectangle callouts, save versions, and download the annotated PDF.

### Additional PDF Workflows

- **PDF/A Validator**: https://pdfcheck.online/pdf-a-validator
- **Batch PDF Checker**: https://pdfcheck.online/batch-pdf-checker
- **PDF Text Extractor**: https://pdfcheck.online/pdf-text-extract
- **PDF to Markdown**: https://pdfcheck.online/pdf-to-markdown
- **PDF Font Checker**: https://pdfcheck.online/pdf-font-checker
- **Compare PDFs**: https://pdfcheck.online/pdf-compare
- **PDF to Image**: https://pdfcheck.online/pdf-to-image
- **Merge PDF**: https://pdfcheck.online/merge-pdf
- **Split PDF**: https://pdfcheck.online/split-pdf
- **PDF Password Tool**: https://pdfcheck.online/pdf-password
- **PDF Metadata Editor**: https://pdfcheck.online/pdf-metadata-editor
- **PDF Metadata Remover**: https://pdfcheck.online/pdf-metadata-remover
- **PDF Converter Directory**: https://pdfcheck.online/pdf-converter
- **All PDF Tools**: https://pdfcheck.online/all-pdf-tools

## REST API

### Authentication
Register at https://pdfcheck.online/register to create API tokens. Include token in Authorization header:
```
Authorization: Bearer YOUR_API_TOKEN
```

### Endpoints

#### Analyze PDF
```
POST /api/v1/pdf/analyze
Content-Type: multipart/form-data

Parameters:
- file: PDF file (required, max 100MB)
- is_public: boolean (optional, default false)

Response: JSON with metadata, software info, timestamps, share_token
```

#### Get Analysis Results
```
GET /api/v1/pdf/{id}

Response: JSON with full analysis data
```

#### Get User Info
```
GET /api/v1/user

Response: JSON with usage stats, remaining quota
```

### Rate Limits
Current limits vary by interface and plan. Use the API documentation and authenticated usage endpoint as the authoritative sources.

## Privacy & Security

- **Secure Processing**: Files processed in memory, not permanently stored
- **HTTPS**: All data transferred via encrypted connection
- **Data Retention**: Analysis results retained 30 days, then deleted
- **Shareable Links**: Results can be shared via unique tokens

## Tools Directory

Comprehensive database of PDF software signatures:
**URL**: https://pdfcheck.online/pdf-tools

Categories include:
- PDF Editors (Adobe Acrobat, Foxit, Nitro)
- Office Suites (Microsoft Office, LibreOffice, Google Docs)
- Design Tools (Canva, Figma, Adobe Creative Suite)
- Programming Libraries (iText, PDFBox, ReportLab, pdf-lib)
- AI/LLM Tools (ChatGPT exports, Claude artifacts, etc.)

## Resources

- **How It Works**: https://pdfcheck.online/how-it-works
- **API Documentation**: https://pdfcheck.online/api-docs
- **MCP Server**: https://pdfcheck.online/mcp-server
- **AI Agents Guide**: https://pdfcheck.online/ai-agents
- **Sitemap**: https://pdfcheck.online/sitemap
- **About**: https://pdfcheck.online/about
- **Privacy Policy**: https://pdfcheck.online/privacy

## AI Agent Integration

### MCP Server (Recommended)
Endpoint: https://pdfcheck.online/api/mcp (Streamable HTTP — no downloads needed)
Compatible with: Claude Desktop, GitHub Copilot, Cursor, Windsurf, and any MCP client.

Config (add to your AI tool):
```json
{
  "mcpServers": {
    "pdfcheck": {
      "url": "https://pdfcheck.online/api/mcp"
    }
  }
}
```

Available MCP tools: analyze_pdf, get_analysis, list_analyses, check_usage

### REST API
Base URL: https://pdfcheck.online/api/v1
- POST /pdf/analyze — Upload and analyze a PDF (multipart/form-data)
- GET /pdf/{token} — Retrieve analysis results
- GET /pdf — List all analyses
- GET /user — Check usage quota

### CLI Tool
Wrap the API in a bash function:
```bash
pdfcheck() {
  curl -s -X POST "https://pdfcheck.online/api/v1/pdf/analyze" \
    -H "Authorization: Bearer $PDFCHECK_API_TOKEN" \
    -F "file=@$1" | jq .
}
```

### Rate Limits
- API tokens: Generate at https://pdfcheck.online/account/api-tokens

### Machine-Readable Discovery
- LLM summary: https://pdfcheck.online/llms.txt
- XML sitemap index: https://pdfcheck.online/sitemap.xml
- API catalog: https://pdfcheck.online/.well-known/api-catalog
- Agent skills: https://pdfcheck.online/.well-known/agent-skills/index.json
- MCP server card: https://pdfcheck.online/.well-known/mcp/server-card.json
- OAuth protected-resource metadata: https://pdfcheck.online/.well-known/oauth-protected-resource

### PDF Skills for AI Agents
Downloadable skill files available at https://pdfcheck.online/ai-agents#pdf-skills:
- PDF Analysis Skill — Metadata extraction, anomaly detection, structured reporting
- PDF Generate Skill — Create PDFs using ReportLab, pdf-lib, Puppeteer, WeasyPrint
- PDF Validation Skill — Structure validation, PDF/A compliance, accessibility checking
- PDF Workflow Skill — Chain operations: analyze → validate → optimize → deliver

## Technical Details

### Supported PDF Versions
PDF 1.0 through PDF 2.0

### File Size Limits
- Web upload: 100MB
- API upload: 100MB

### Analysis Methods
1. XMP metadata extraction
2. Document Information Dictionary parsing
3. Binary structure analysis
4. Software signature matching
5. Timestamp cross-validation
6. Incremental update detection

## Contact

- **Website**: https://pdfcheck.online
- **Email**: support@businesspress.io