langchain-pdf

Generate clean, readable, professional PDFs from raw text or Large Language Model (LLM) output.

langchain-pdf is designed for developers who want deterministic, well-formatted documents instead of messy markdown or broken PDFs.

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✨ Why langchain-pdf?

Large Language Models often generate:

• markdown artifacts (**bold**, ---, 1. lists)
• inconsistent spacing
• duplicated headings
• orphan bullets
• blank pages in PDFs

langchain-pdf fixes all of that.

It introduces a proper document pipeline:

LLM Output → Normalize → Parse → Render → PDF

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🚀 Features

• 🧠 Robust text normalization (handles messy LLM output)
• 📚 Structured document parsing (headings, paragraphs, bullets)
• 🖨️ Professional PDF rendering
• 🛑 No blank pages or orphan content
• 🔗 LangChain integration (Gemini ,OpenAI , Anthropic supported)
• 💻 CLI support (no Python code required)
• 🧪 Windows-tested (PowerShell friendly)
• 📦 Open-source & extensible

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📄 Sample Outputs

Want to see what the generated PDFs look like?

👉 Check out the sample outputs here:
docs/outputs/

📦 Installation

Clone the repository

git clone https://github.com/your-username/langchain-pdf.git
cd langchain-pdf

Create and activate a virtual environment

python -m venv venv

Windows

venv\Scripts\activate

macOS / Linux

source venv/bin/activate

Install dependencies

pip install -r requirements.txt
pip install -e .

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Set ONE of the following environment variables:

• OPENAI_API_KEY (OpenAI)
• GOOGLE_API_KEY or GEMINI_API_KEY (Google Gemini)
• ANTHROPIC_API_KEY (Anthropic)

🔐 Environment Setup (for AI generation)

Create a .env file in the project root:

GOOGLE_API_KEY=your_gemini_api_key_here
OPENAI_API_KEY=your_gemini_api_key_here
ANTHROPIC_API_KEY=your_gemini_api_key_here

Optional LLM Providers

OpenAI:

pip install langchain-openai

Google Gemini:

pip install langchain-google-genai

Anthropic:

pip install langchain-anthropic

.env is ignored by Git and should never be committed.

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🖥️ CLI Usage

1️⃣ Convert a text file to PDF

python -m langchain_pdf.cli input.txt output.pdf

Optional title:

python -m langchain_pdf.cli input.txt output.pdf --title "My Document"

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2️⃣ Generate a PDF using LangChain (Gemini)

python -m langchain_pdf.cli \
  --topic "Generative AI with LangChain" \
  --out reports/course.pdf

This will:

• generate content using Gemini
• normalize messy output
• create a clean PDF automatically

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3️⃣ Help

python -m langchain_pdf.cli --help

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🧠 How It Works (Architecture)

┌──────────────┐
│  LLM / Text  │
└──────┬───────┘
       ↓
┌──────────────┐
│ Normalizer   │  ← removes markdown, noise, duplicates
└──────┬───────┘
       ↓
┌──────────────┐
│ Parser       │  ← converts text → document blocks
└──────┬───────┘
       ↓
┌──────────────┐
│ Renderer     │  ← layout-safe PDF rendering
└──────┬───────┘
       ↓
┌──────────────┐
│   PDF File   │
└──────────────┘

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📁 Project Structure

docs/
├── outputs/
│   ├── course_overview_sample.pdf
│   ├── resume_sample.pdf
│   └── README.md
langchain-pdf/
│
├── langchain_pdf/ # Core library
|   ├──assets/
|      ├──fonts/
|        ├── DejaVuSans.ttf
|        ├── DejaVuSans-Bold.ttf
|        ├── LICENSE.txt
│   ├── __init__.py
│   ├── exporter.py
│   ├── normalizer.py
│   ├── parser.py
│   ├── renderer.py
│   ├── templates.py
│   └── cli.py
│
├── examples/             # Usage examples (not packaged)
│   ├── llm_factory.py
│   └── langchain_example.py
│
├── tests/                # Tests (optional)
│
├── README.md
├── requirements.txt
├── pyproject.toml
└── .env.example

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🧪 Example Use Cases

• Generate course PDFs from LLMs
• Convert AI-generated reports into readable documents
• Create resumes, study material, or technical notes
• Build SaaS features that export PDFs
• Automate documentation pipelines

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🤔 Is this made with AI?

Yes — and engineered by a human.

AI helps generate content. langchain-pdf ensures that content is structured, readable, and professional.

The value is not generation — it’s control.

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🛠️ Extending the Project

Planned / easy extensions:

• Support for local LLMs (Ollama)
• Batch PDF generation
• Themes (fonts, spacing)
• DOCX export
• Stream / stdin input

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🤝 Contributing

Contributions are welcome.

If you:

• improve normalization
• add render themes
• support new LLMs

feel free to open a PR.

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📜 License

MIT License — free to use, modify, and distribute.

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⭐ Final Note

If you are tired of broken PDFs from AI output, langchain-pdf is built for you.

🔤 Fonts & Attribution

This project bundles the Inter font for consistent, readable PDF output.

Inter is licensed under the SIL Open Font License (OFL 1.1)
Font copyright © The Inter Project Authors.

The font license is included in: langchain_pdf/assets/fonts/LICENSE.txt