๐Ÿš€ Free Alternative to Paid PDF APIs – How to Chunk Large PDFs for AI or Automation

Ever tried uploading a 50MB PDF to an AI service or automation tool, only to hit a file size error?

This guide shows you how to bypass those limits with a free, open-source workflow that chunks massive PDF files into smaller, manageable parts โ€” perfect for feeding into AI models, parsing tools, or cloud storage.

Built on top of N8N and a self-hosted PDF chunking microservice, this workflow is fast, flexible, and fully customisable. Whether youโ€™re prepping files for Gemini, Claude, ChatGPT, OCR, or even internal review โ€” this tool makes it possible.


๐Ÿ” Why You Need PDF Chunking

Most automation tools and AI APIs choke on large PDFs due to:

  • Max upload sizes (often 5MBโ€“20MB)
  • Page count restrictions
  • Timeouts or memory constraints

This setup eliminates those limits by:

  • ๐Ÿงฉ Breaking down PDFs into smaller chunks (by size or page count)
  • ๐Ÿ” Returning download links for each chunk
  • ๐Ÿง  Allowing each chunk to be processed independently in any workflow

๐Ÿ›  What Youโ€™ll Get

  • โœ… N8N workflow file (drag & drop ready)
  • โœ… Custom PDF chunking microservice using pdf-lib
  • โœ… Setup guide for Ubuntu (works with any VPS)
  • โœ… Gemini prompt example (optional, not required)
  • โœ… Support for large PDF files

๐Ÿ’ก Real-World Use Cases

  • Feed chunks into AI tools like Gemini, OpenAI or Anthropic
  • Upload to cloud storage or backup systems without hitting file limits
  • Pass through OCR or document extraction services in batches
  • Split course materials or books into manageable parts
  • Pre-process for searchable indexing or embeddings

๐Ÿง  Gemini-Compatible, but Not Locked In

The example workflow includes a Gemini Document Vision fo analysing each PDF chunk, but you can swap these nodes to do whatever you want your PDF chunks.


๐Ÿš€ Get Started

  1. Download the workflow and install guide
  2. Set up the chunking service on your server (10 mins)
  3. Connect your PDF input source (Google Drive, upload, etc.)
  4. Use the chunked files however you want!

๐Ÿ”“ Free, Open, and Yours to Control

Unlike paid APIs that gate your usage, this solution runs on your own terms, with:

  • No file size limits
  • No rate caps
  • No hidden costs

Just host it, and start processing.

๐Ÿ‘‰