PDF OCR — Make Scans Searchable

What "searchable PDF" means

A searchable PDF looks identical to the original scan but has invisible text positioned over each scanned word. Search tools (Ctrl-F in Acrobat / Preview / browsers), copy-paste, and screen readers can all access the text.

When this works well

• Clean scans of printed text — 200+ DPI, straight pages, good contrast — accuracy 95%+
• Modern documents — books, reports, invoices, modern letters

When it struggles

• Handwritten content — Tesseract is print-trained; accuracy drops sharply
• Low-resolution / skewed scans — pre-process first (straighten, sharpen)
• Decorative or display fonts — Tesseract trained on standard text fonts
• Tables and forms — text is extracted but layout / column structure is lost

Privacy

Tesseract.js runs entirely in your browser via WebAssembly. Language model files come from cdnjs. Your PDF and the OCR'd text never leave the page.