About OCR PDF – Extract Text from Scanned Documents

Optical Character Recognition (OCR) transforms scanned pages, photographed documents, and image-based PDFs into searchable, selectable, and copyable text. This is essential when working with legacy documents, scanned archives, photographed receipts, or any PDF where the content was captured as an image rather than generated digitally.

LocalPDF's OCR tool is uniquely privacy-preserving: the entire recognition process runs on your device using Tesseract.js, a client-side OCR engine built on WebAssembly. Your scanned documents are never transmitted to a cloud service or remote server. All text recognition happens locally in your browser, using your own device's processing power.

The tool supports multiple recognition languages and produces output as extracted plain text that you can copy, search, and use freely. It works on both image-only PDFs (scanned documents) and mixed PDFs where some pages are scanned and others are digitally generated.

How to Use

  1. 1Upload your scanned or image-based PDF using the file selector.
  2. 2Select the primary language of the document for best OCR accuracy.
  3. 3Click "Run OCR" to begin text recognition. This may take a moment for multi-page documents.
  4. 4Review the extracted text in the output panel and copy or download it.

Key Features

Fully Local Processing

OCR runs entirely in your browser using Tesseract.js over WebAssembly. Your scanned documents are never sent to any server.

Multi-Language Support

Choose from multiple recognition languages to maximize accuracy for documents in English and other supported languages.

Works on Any Image PDF

Compatible with scanned documents, photographed pages, fax conversions, and any PDF where content is stored as raster images.

Instant Text Output

Extracted text is presented immediately in a copyable panel so you can use it directly without downloading additional files.

Frequently Asked Questions

What types of documents work best with OCR?

OCR works best on clearly scanned documents with high contrast between text and background, standard fonts, and good resolution (at least 200 DPI). Handwritten text, decorative fonts, and very low-quality scans produce less accurate results.

How accurate is the text recognition?

For clearly printed, high-resolution documents in supported languages, accuracy is typically 95 to 99 percent. Accuracy decreases for skewed pages, degraded originals, or documents with complex multi-column layouts.

Can I use OCR on a PDF that already has selectable text?

Yes, but it is unnecessary. If your PDF already contains selectable text (you can highlight it with your mouse), the text is already digital. OCR is specifically for image-based content where no text layer exists.

Does OCR work for documents in languages other than English?

Yes, Tesseract supports many languages. Select the appropriate language before running recognition to get the best results.

Is there a page limit for OCR processing?

There is no imposed limit, but OCR is computationally intensive. Very long documents (50 or more pages) may take several minutes to process. Processing time scales with document length and image resolution.