OCR PDF Online — Free, Make Scanned PDFs Searchable, No Sign-Up
Use optical character recognition (OCR) to add a searchable text layer to scanned PDFs. Select and copy text from any image-based document. Free, powered by Tesseract.
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How to Run OCR on a PDF — 3 simple steps
Scanned PDFs are just images — you cannot search, select or copy any text. PdfDocShift uses Tesseract OCR, the most widely used open-source OCR engine, to analyse each page and add an invisible, searchable text layer. The result is a fully searchable PDF that looks identical to the original.
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What Is OCR and Why Do You Need It?
OCR stands for Optical Character Recognition. When you scan a physical document, the result is a PDF that is essentially a photograph — the text is an image, not actual selectable characters. You cannot search it, copy text from it, or use it with screen readers. OCR analyses the image pixel-by-pixel and identifies characters, words, and paragraphs, then embeds a text layer behind the visible image. The result looks identical to the original scan but is fully searchable, copy-pasteable, and accessible. This is essential for scanned contracts, archived records, scanned books, historical documents, and any digitised paperwork you need to work with programmatically.
What Affects OCR Accuracy?
Three factors dominate OCR accuracy. First, scan resolution: 300 DPI produces excellent results; 150 DPI is acceptable for clean text; below 150 DPI, accuracy drops sharply. Second, contrast: black text on white paper is ideal. Faded, yellowed, or low-contrast documents cause character misreads. Third, font clarity: printed text from a laser printer is much more reliably recognised than handwriting, decorative fonts, or typewritten text from older typewriters. For difficult documents, pre-processing the scan to increase contrast and resolution before running OCR can significantly improve results.
After OCR — Searching and Editing
Once OCR is complete, the output PDF is fully searchable in any PDF viewer — use Ctrl+F (or Cmd+F on Mac) to search for any word or phrase. The recognised text can also be selected and copied. If you need the text in a fully editable format, convert the OCR'd PDF to Word using the PDF to Word tool immediately after. Bear in mind that OCR is not 100% perfect — proper nouns, technical terms, and unusual formatting may need manual correction before the document is used in a professional context.
OCR PDF questions
Everything you need to know about using OCR PDF online for free.
OCR (Optical Character Recognition) reads text from images and adds a searchable text layer to your PDF. Scanned PDFs are just images — after OCR you can search, copy and edit the text.
PdfDocShift's OCR tool supports English, German, French and Spanish. The OCR engine (Tesseract) automatically detects text regardless of language, but accuracy is best for the supported languages.
OCR time depends on the number of pages and scan quality. A typical 10-page scanned document completes in 15–30 seconds. Very large documents (100+ pages) may take up to 2 minutes.
No. OCR adds an invisible text layer beneath the existing page images. The visual appearance of each page remains exactly the same — only searchability and text selection are added.