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OCR PDF

Recognise the text on a scanned PDF and add an invisible layer so the file becomes searchable. It runs on your own device — the scan is never uploaded.

Runs on your deviceFree, unlimitedAI text recognition, on your device

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Accepts .pdf · One file at a time · up to 150 MB each "Upload" and "download" here mean your browser reading a file from this device and writing one back to it. Your file is never sent to a server — open your browser's network panel and watch: no request carries your file.

OCR PDF FAQ

How is this different from every other OCR tool?

Where the work happens. Recognition is the one PDF feature the whole industry runs on its own servers, so making a scan searchable means sending it somewhere — and the scans people need this for are contracts, invoices, medical records and certificates. Here the model runs in your browser: it is downloaded once, about 21 MB, and after that the file never leaves the machine. You can watch the network panel while it works: no request carries the file.

How accurate is it, honestly?

Good, and not guaranteed. On a sixteen-page test set rendered with a 0.3 degree skew — because a real scan always has some — character recall measured 95.2%. Clean, straight pages score higher; stamps, handwriting, faint photocopies and pages photographed at an angle score lower, sometimes much lower. Treat it as making a document findable rather than as a transcript: the words you search for will usually be there, and a legal-grade transcription this is not.

Does the scan itself change?

No, and this is checked rather than asserted: after a run, the SHA-256 of every image stream in the output matches the input exactly. The pages are never decoded, re-encoded or resized — only a text layer and its font description are added, which came to 5.1 KB on a two-page scan. If you also want the file smaller, compress it afterwards rather than instead: compression re-encodes the images, and doing that first would give the recogniser less to read.

Can I see or select the added text?

You cannot see it, and you can select it. The text is written in the rendering mode that paints nothing, positioned over the words it came from, so the page looks untouched while search, copy and screen readers all find the words. That also means no font is embedded — the glyphs are never drawn, so only the character mapping is needed, and the font costs zero bytes. The output was read back through two independent PDF engines rather than only the one we use, and both returned the same Chinese text.

What if the PDF already has text in it?

It is left alone and the tool says so. A PDF exported from Word is already searchable, and putting a recognition layer on top would make every search match twice and every copy come out doubled. What the tool checks is whether the pages carry text at all, sampled through the document; if they do, there is nothing here to add.

How long does it take?

A few seconds per page for an ordinary Chinese or English page — measured at 2.4 to 4.0 seconds on a desktop with hardware acceleration — plus the one-time model download. A dense two-column academic page, four thousand characters, took about fourteen. The cost tracks how much text is on the page rather than the page size, and a phone will be several times slower.

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