OCR a PDF: make a scanned PDF searchable
A scanned PDF is just pictures of pages: you cannot search it, copy from it or have it read aloud. OCR recognizes the text and puts it back into the PDF, invisibly, exactly over each word.
Drop the scanned PDF you want to add text to
or pick a file from your device
- Open the scanned PDF. CLEKARA tells you how many pages have no text.
- Choose the document's language and the quality: Fast (200 dpi) or Accurate (300 dpi) for small print.
- Press Run OCR and download the searchable PDF, plus the text as a .txt file if you want it.
How the text gets into the PDF
Each page is drawn at 200 or 300 dpi and read by Tesseract, the open-source OCR engine originally developed at HP and later by Google, compiled to WebAssembly and running inside your browser. It uses the LSTM neural-network models for the language you choose.
Tesseract returns every word with its exact position. CLEKARA writes those words as an invisible text layer and places it over the original page, so the PDF looks exactly the same — the scanned image is not touched or recompressed — but you can now search it with Ctrl+F, select and copy text, and screen readers can read it. Pages that already have text are skipped unless you ask otherwise.
Worth knowing
OCR is very accurate on clean printed text and less so on handwriting, photos taken at an angle, very low resolution scans or decorative fonts. The result shows the average confidence so you know how much to trust it.
The first time, the engine and language data (about 10 MB) are downloaded and then cached. Each page takes one to a few seconds; long documents are faster on a computer.
Frequently asked questions
How do I make a scanned PDF searchable?
Open it here, pick the language and press Run OCR. The downloaded PDF can be searched with Ctrl+F and its text can be copied.
Does OCR change how my PDF looks?
No. The original page image stays exactly as it was; the text is added as an invisible layer on top.
Which languages are supported?
English, Spanish, Portuguese and French, alone or combined.
Is my document uploaded?
No. Recognition runs inside your browser; the PDF never leaves your device.
Can I just get the text?
Yes. Besides the searchable PDF you can download the recognized text as a .txt file or copy it.