PDFree › Blog › How to OCR a PDF Without Uploading It
4-minute read · Updated August 2026
You have a scanned PDF — a contract, a medical record, an old receipt — and you need to search it, copy text out of it, or just make it selectable. Most free OCR tools want you to upload the file to their servers first. Here's how to do it entirely in your browser instead, so the scan never leaves your device.
OCR is often run on the documents people are most protective of — signed contracts, medical intake forms, financial statements, ID scans. Uploading one of these to a third-party server for recognition means a copy of it exists somewhere outside your control, even if the vendor promises to delete it afterward. Browser-based OCR sidesteps the question entirely: there's no upload step, so there's no copy to worry about.
This works because of Tesseract.js, a WebAssembly port of the open-source Tesseract OCR engine. It runs the same recognition pipeline a server would, just on your own CPU instead of someone else's.
Go to pdfree.io/ocr-pdf/. Nothing to install or register.
Click "Choose files" or drag your PDF onto the page. It's read locally — not uploaded to any server.
Click "Install OCR Engine" to load Tesseract.js — around 17 MB, downloaded once and cached in your browser for next time. Pick your document's language from the dropdown; 18 languages are supported, including English, Spanish, French, German, Russian, Arabic, Japanese, Chinese, Korean, and Hindi. PDFs that already have a text layer skip this step automatically.
Click "Run OCR." Each page is recognized in your browser and an invisible, selectable text layer is embedded on top of the original scan — the page still looks identical, but you can now select, search, and copy the text. Download the searchable PDF when it's done.
The output isn't a new document with re-typed text — it's your original scanned page with an invisible text layer placed precisely over the recognized words. Visually, nothing changes. Functionally, you can now:
Yes — when the recognition happens locally. Your file is never transmitted anywhere during OCR with PDFree: not the original scan, not the recognized text, not even metadata about the operation. This is a structural guarantee, not a privacy policy — PDFree has no server-side OCR infrastructure and is open source (GNU AGPLv3), so it can be verified rather than taken on trust.
By contrast, most free OCR services (including some well-known PDF tools) send your document to their servers to run recognition, even if they delete the copy afterward. For medical records, contracts, or anything with personally identifiable information, browser-based OCR removes that exposure entirely.
No. PDFree runs Tesseract.js — an open-source OCR engine compiled to WebAssembly — directly in your browser. Text recognition happens on your own device's CPU. The scanned file and the recognized text never travel over the network.
Tesseract.js is the same open-source OCR engine (Tesseract) used by many server-side tools, just compiled to run in the browser. Accuracy depends mainly on scan quality — a clean 300 DPI scan typically recognizes at 95%+ character accuracy for printed text, whether the engine runs locally or on a server.
18 languages: English, French, German, Spanish, Italian, Portuguese, Russian, Uzbek, Dutch, Polish, Turkish, Arabic, Japanese, Chinese (Simplified and Traditional), Korean, Hindi, and Thai.
No artificial limit is imposed by PDFree. The practical limit is your device's available memory — very large scanned documents (hundreds of pages) may take longer since recognition runs page by page on your own hardware.
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