PDF OCR Text Extraction — Free, Browser, Tesseract
Extract text from scanned PDFs using OCR (Tesseract.js). Multilingual. Browser-only — no upload.
About 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
- Drop scanned PDF. PDF rendered to image at high DPI (300+).
- Run OCR per page. Tesseract.js processes each page image. Models loaded lazily based on chosen languages.
- Reconstruct text. Per-line text emitted in reading order with confidence scores.
- 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.
Pro 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.
Reviewed by Ahsan Mahmood · Last updated 2026-05-06 · Part of ZTools.
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