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pdf-ocr-text-extraction

OCR (Optical Character Recognition) extracts text from images of text — scanned PDFs, photographed documents, screenshots. The ZTools PDF OCR tool runs Tesseract.js (the JavaScript port of Google's Tesseract OCR engine) entirely in the browser: no upload, no signup, supports 100+ languages. Quality depends on the source image — clean print scans give 98%+ accuracy; handwriting and noisy scans struggle. Slower than non-OCR text extraction (each page takes 2-10 seconds) but the only option for scanned / image-based PDFs.

Use cases​

Digitise a scanned book / magazine​

No embedded text in the PDF; OCR reads the page images. Output as searchable text.

Process a fax-scanned contract​

Faxes are image-only. OCR makes the text usable for downstream search / copy.

Extract text from screenshots embedded in PDFs​

A report with screenshots of code. OCR reads the code text.

Multilingual document processing​

Tesseract supports 100+ languages — Arabic, Chinese, Russian, Spanish, French, etc.

How it works​

  1. Drop scanned PDF — PDF rendered to image at high DPI (300+).
  2. Run OCR per page — Tesseract.js processes each page image. Models loaded lazily based on chosen languages.
  3. Reconstruct text — Per-line text emitted in reading order with confidence scores.
  4. Output — Plain text. Optional: confidence highlighting (low-confidence words flagged).

Examples​

Input: 10-page scanned contract, English

Output: ~3000 words extracted. Tesseract takes ~20-30 seconds total. Accuracy 95-98% on clean scans.

Input: Multilingual scan (English + French)

Output: Toggle "eng+fra" model. Tesseract handles both. Slower load time on first use.

Input: Handwritten notes

Output: Tesseract struggles with handwriting (typically 60-80% accuracy). For handwriting, use Google Cloud Vision or Azure Form Recognizer.

Frequently asked questions​

How accurate is it?

Clean print: 95-99%. Slightly noisy: 85-95%. Handwriting / poor scans: 60-80%. Always proofread important documents.

Why is the first run slow?

Tesseract.js downloads language models (~10 MB per language) the first time. Subsequent runs are cached.

Maximum PDF size?

Browser memory is the limit. 50-100 page scans work; beyond that, split the PDF first.

Privacy?

All processing in the browser. PDF never uploaded.

Tips​

  • For best accuracy, use the highest-resolution scan available. 300 DPI minimum.
  • For multilingual docs, only enable the actual languages — extra models slow processing.
  • For long documents, split into 10-page chunks — easier to recover from a tab crash.
  • For handwriting, use a cloud OCR service. Tesseract is print-optimised.

Try it now​

The full pdf-ocr-text-extraction runs in your browser at https://ztools.zaions.com/pdf-ocr-text-extraction — no signup, no upload, no data leaves your device.

Open the tool ↗

Last updated: 2026-05-06 · Author: Ahsan Mahmood · Edit this page on GitHub