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OCR a scanned PDF without uploading it.

Recognition runs on your device. Slower than a server, and the scan never leaves.

Open OCR a PDF

Why OCR is almost always done by upload

Recognising text in an image is real computation, and for years the only practical place to do it was a server. So every mainstream OCR service works by upload, and the documents people run through OCR are overwhelmingly the ones they would least want uploaded: they are scans, and scans are what medical letters, contracts, bank correspondence and identity documents arrive as.

The format forces the issue. A scan has no text layer. Until the words are recognised, you cannot search it, quote it, or copy from it. That need is what sends sensitive documents to OCR services in the first place.

What happens here instead

Tesseract, the open-source OCR engine, is compiled to WebAssembly and runs in this browser tab. The engine and its English language data are about 6 MB and download once, then stay cached. Each page is rendered with PDF.js, recognised on your device, and the result is assembled here.

You get two outputs. A searchable PDF — the scan exactly as it was, with the recognised words laid invisibly on top so search, select and copy work. Or the plain text, for quoting and pasting.

The honest trade

It is slower than a server. A page takes a couple of seconds on a laptop and noticeably longer on a phone, because recognition is CPU work and your device is doing it. Accuracy is the same engine most server tools use, and it depends on the scan: good on clean 300 DPI printed text, worse on skewed pages and low resolution, and not usable on handwriting. Sending a document to a server does not change any of that.

How to verify

Developer tools → Network → run OCR on a scan. You will see the engine download once, coming in. Nothing carries the document out. The general method applies to any OCR site.

Open DevTools → Network → run a conversion. There is no upload endpoint to receive a file.

Common questions

Can I OCR a PDF without uploading it?

Yes. Tesseract runs as WebAssembly in your browser tab. The scan is rendered and recognised on your device and nothing is transmitted.

Why is it slower than an online OCR service?

Because your device does the recognition rather than a server. A page takes a couple of seconds on a laptop and longer on a phone. That is the trade for the scan never leaving.

Does it produce a searchable PDF?

Yes. The searchable PDF keeps every page as scanned and adds the recognised words as an invisible text layer, so search and select work.

Is the accuracy worse than a server tool?

No. It is the same engine class most server tools use. Accuracy depends on the scan, not on where it runs.

What about a scan that is a photograph rather than a PDF?

Image to Text does the same recognition on a JPG or PNG, also on your device.

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