OCR PDF — Extract Text from Scanned Documents

OCR PDF makes scanned documents searchable by adding a hidden text layer behind page images. It helps turn flat scans into PDFs where words can be searched, copied, indexed locally, or used by assistive workflows.

What happens in the browser

The browser renders each page image, runs optical character recognition with a client-side OCR engine, and writes recognized text back into the PDF as an invisible layer aligned to the visual page.

Step-by-step workflow

  1. Choose a scanned or image-based PDF.
  2. Select the language if the tool offers language options.
  3. Run OCR and wait for page-by-page processing.
  4. Download the searchable PDF.
  5. Test the result with Ctrl+F or text selection.

When this tool is useful

  • Searching old scanned statements or invoices.
  • Making course notes and research scans easier to find.
  • Preparing image PDFs before conversion to Word or Excel.
  • Improving local document indexing on a computer.

Limitations to know before downloading

  • Handwriting, blur, skew, and low-resolution photos reduce accuracy.
  • Large documents can take several minutes because OCR is CPU-intensive.
  • OCR adds text recognition; it does not visually redesign poor scans.

Privacy and file handling

OCR is performed in the browser rather than through a cloud OCR API. Page images are not uploaded for recognition.

OCR for PDFs — turning scans into searchable documents

A scanned PDF looks like a normal PDF but behaves like a photo album: you cannot select, copy, or search any of the text because internally each page is a single flat image. Optical Character Recognition analyses those images pixel by pixel and reconstructs the characters, then this tool writes them back into the PDF as an invisible text layer aligned to the visible words.

How the OCR engine works here

We use Tesseract.js — the WebAssembly port of Google's Tesseract engine, the same OCR that powers Google Books. It runs entirely in your browser. For each page we render a high-resolution bitmap with PDF.js, feed it to Tesseract, then attach the resulting bounding boxes as an invisible text layer via pdf-lib. The visible page never changes; only a hidden layer of selectable text is added.

Step-by-step

  1. Upload a scanned PDF (or any image-based PDF).
  2. Wait while each page is rendered and analysed. Progress updates per page.
  3. Download the result. It looks identical but is now searchable in every PDF viewer and indexable by Spotlight, Windows Search, and Google Drive.

When OCR does — and does not — work well

Accuracy is a function of scan quality. 300 DPI black text on a white background from a modern flatbed will score above 98%. Phone photos of curled pages, handwriting, faded receipts, and heavy colour backgrounds drop that to 60–80%. Two techniques help: increase contrast in a preprocessing step, and de-skew rotated pages with our Rotate PDF tool before running OCR.

Privacy note

OCR normally means sending confidential scans — passports, tax returns, medical records — to a cloud API. Because everything here runs in the browser tab, the pages never leave your device. You can literally disconnect from the internet after the page loads and OCR will still complete.