How to OCR a PDF Online Free
Quick answer: Open OCR PDF, drop your scanned PDF, choose a language and output (searchable PDF or text), and download. All processing happens in your browser.
Table of Contents
You have a scanned PDF — a contract, an old book, a handwritten form — and you need to search it for specific text. Without OCR (Optical Character Recognition), the document is just a picture. You can't copy text, search for keywords, or extract quotes.
Here's how to OCR a PDF online free using PDFslime's OCR tool, which keeps your files private.
What Is OCR
OCR analyzes images of text and converts them into machine-readable characters. When you OCR a scanned PDF, the tool:
- Analyzes each page image to identify text regions.
- Recognizes individual characters using a trained recognition model.
- Overlays the recognized text onto the original page as an invisible, selectable layer.
- Produces a PDF where you can search, copy, and highlight text.
The result looks identical to the original scan, but the text underneath is now selectable and searchable.
Why OCR a PDF
- Searchability: find any word or phrase instantly across hundreds of pages.
- Text extraction: copy quotes, data, or passages for use elsewhere.
- Accessibility: screen readers can read the text aloud.
- Archiving: make historical documents searchable for research.
How to OCR a PDF Online Free
Drop scan
Load your scanned PDF into the browser
Run OCR
Tesseract.js processes every page locally
Download
Searchable PDF or plain text — no uploads
- Open OCR PDF in any modern browser.
- Drag and drop your scanned PDF onto the page.
- Select the document's language.
- Choose your output: Searchable PDF (keeps the original look, adds an invisible text layer) or Text only (a plain .txt extract).
- Click Run OCR — processing runs entirely in your browser using Tesseract.js.
- Download your result.
No server calls, no uploads — the recognition model downloads once from a public CDN and everything else happens on your device.
How Accurate Is Browser-Based OCR
| Document type | Typical accuracy | Best practices |
|---|---|---|
| Clean printed text | 99%+ | 300 DPI, good contrast |
| Typewritten documents | 95-98% | Clear fonts, no smudges |
| Books & magazines | 90-97% | Flat pages, even lighting |
| Handwritten notes | 60-80% | Legible writing required |
| Low-quality scans | 50-70% | Rescan at higher DPI if possible |
For best results, scan at 300 DPI or higher with good lighting and contrast.
Best Use Cases for PDF OCR
- Legal documents: make contracts and filings searchable.
- Academic research: OCR old papers and journal articles for citation.
- Business operations: process invoices and receipts for quick lookup.
- Personal archives: digitize family letters and historical documents.
Frequently Asked Questions
Yes. PDFslime's OCR tool is completely free with no page or file-size limits beyond what your device can handle.
It depends on page count and your device — OCR is CPU-intensive. A short document typically finishes in well under a minute; larger scans take longer.
Yes. Recognition happens in your browser using Tesseract.js. Your document never leaves your device.
English, Spanish, French, German, Portuguese, and Italian are built into the language picker.