How is this different from PDF to Markdown or PDF to Word?
Those two read the characters a PDF already contains, which is fast and exact. This one is for the documents that contain none — a scan is a picture of text — and it recognises the shapes instead. If your PDF has a text layer this tool will tell you so and send you to them, because reading what is there always beats guessing at it.
How accurate is it?
On a clean, flat scan of printed type, high enough to paste and skim: measured on a synthetic 200 dpi scan, 0.2% of characters wrong in English, 0.7% in Portuguese, 0.6% in Russian. On a phone photograph of a curved page in poor light, low enough that you should read it against the original. The lines the reader was least sure of are listed, so the checking has somewhere to start rather than being a guess about a guess.
Do I get a searchable PDF back?
Yes. The recognised lines are written invisibly over the original scan, each at the position it was found, in a font that draws nothing — the same construction Tesseract's PDF output has used for a decade. Any viewer can then search, select and copy the text while showing only the scan. Before the file is offered it is opened again and its text read back, and the result panel says whether every page passed.
How long does a long document take?
About 0.6 seconds a page on a graphics card, measured on an Apple M4 Mac; about two seconds a page on one processor thread in Chrome and six to eleven in Safari; plus the seventeen-megabyte download the first time. Pages are drawn, read and released one at a time, so a long document costs time rather than memory. Phones were not measured.
Which languages does it read?
English and forty-six other Latin-script languages, Chinese and Japanese with the model that loads by default. Russian, Ukrainian and Belarusian with a second recogniser you pick in the options, because it is an extra eight megabytes that most visitors should not pay for.
Does the scan leave my device?
No. The renderer, the reader, the models and the recognition all live in this tab. This matters more here than almost anywhere on the site: the documents people scan are contracts, medical letters, payslips and identity papers, and every free online OCR service receives them. Here they are read and nothing is sent.