Make a scanned PDF searchable
Text recognition for scanned pages, run on your own device: the PDF looks the same, but now you can search it and copy from it.
- Nothing is uploaded
- Works offline after first use
- Open source
- No watermark · limit is your device’s memory; phones hold less
Turns a scanned PDF into a searchable PDF by reading the text and laying it invisibly over each page. It is free, needs no account and adds no watermark, and your files are not uploaded: everything runs in your browser on your device. The first run downloads the text reader (about 6 MB) and the WebAssembly engine that runs it to your browser, and after that the tool works offline.
Done
Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
How it works
- Drop one or more scanned PDFs: a contract from the office scanner, receipts photographed with a scanning app, an old manual.
- Leave Scanned pages only chosen, so pages that already have text stay as they are. Tick the box to get the text as a .txt file too.
- Press Read text. Each page takes a few seconds; the note says how many words were found.
In your browser, not on a server
pdf.js (Apache-2.0) renders each page in your tab at 300 dpi (large pages a little less). Tesseract (Apache-2.0), compiled to WebAssembly by tesseract.js with its English LSTM model, finds every word and its box; the engine and model, about 6 MB, are downloaded from this site on first use and cached. pdf-lib (MIT) then writes each word into the page as invisible text (render mode 3) in Helvetica, placed on the word’s baseline and stretched to the word’s width, so a search highlights the right spot. The scanned image itself is not touched. Pages that already have a text layer are skipped unless you ask otherwise.
Compared with upload-based tools: Online OCR services upload the scan to their servers, and free tiers cap pages or files a day. Scans are often the documents people least want copied: IDs, signed contracts, bank and medical letters. Here the reading happens on your device, with no page limit, and the output is your own PDF with a text layer rather than a Word file that loses the layout.
Verify it yourself. Give the page a short while after your first run to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
What does OCR do to my PDF?
A scanned page is a photograph of paper, so a PDF reader cannot search it or copy from it. OCR (optical character recognition) reads the letters in that picture and places the words as invisible text exactly over where they appear. The page looks unchanged, but Ctrl+F finds words and you can select and copy them.
Which languages does it read?
English. Other languages in Latin letters are read with the English model, so expect mistakes, especially in accented letters. Cyrillic, Greek, Arabic, Chinese and other scripts are not read yet.
How accurate is it?
Clean printed text on a straight, sharp scan reads well. Handwriting, faint photocopies, tables with tight lines and photos of pages taken at an angle read worse. The note under the download gives Tesseract’s average confidence, a rough guide to how well it went.
Is my PDF uploaded?
No. The pages are rendered and read in this tab by Tesseract, an open-source OCR engine, so scanned IDs, bank statements and signed contracts never leave your device.
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Guides
- How to make a scanned PDF searchableA scan is a photograph of paper, not text, which is why you cannot search it. Here is how OCR adds a text layer, and a free browser tool for it.