Comment by constantinum

Why PDF parsing is Hell[1]:

Fixed layout and lack of semantic structure in PDFs.

Non-linear text flow due to columns, sidebars, or images.

Position-based text without contextual or relational markers.

Absence of standard structure tags (like in HTML).

Scanned or image-based PDFs requiring OCR.

Preprocessing needs for scanned PDFs (noise, rotation, skew).

Extracting tables from unstructured or visually complex layouts.

Multi-column and fancy layouts breaking semantic text order.

Background images and watermarks interfering with text extraction.

Handwritten text recognition challenges.

[1] https://unstract.com/blog/pdf-hell-and-practical-rag-applica...