What OCR does to your PDF
OCR PDF means optical character recognition: reading the letters in an image and turning them into real text. A scanned document is just pictures of pages, so you can't search it, select a sentence or copy a paragraph. After OCR you can.
ConvertirDocs adds an invisible text layer on top of each page. Nothing visible changes: the scan looks the same, stamps and signatures included. But now you can press Ctrl+F to find a word, highlight text, and copy it into an email or a document.
When it's useful
Think of a stack of scanned invoices where you need to find one supplier, a scanned book chapter you want to quote, or an old contract you have to search for a specific clause. OCR also helps before converting: if you want to turn a scan into an editable document with “PDF to Word” or pull a table into a spreadsheet with “PDF to Excel”, those tools need real text, and OCR provides it.
It's a natural next step after other tools too. If you digitized paper with “Scan to PDF”, or if “Redact PDF” turned some pages into images, OCR makes those pages searchable again.
Accuracy depends on the scan
Recognition is only as good as the image. Sharp, well-lit, straight scans at a decent resolution give the best results. Blurry photos, shadows, tiny print, handwriting and busy backgrounds lead to mistakes: missing words or wrong letters. Because the text layer is invisible, errors won't show on the page, but they will affect search and copy. For important uses, check the copied text.
Choosing the right language helps too. ConvertirDocs supports English, Spanish and Portuguese, and you can select more than one for mixed documents. Pages that already have text are skipped by default, so a PDF that mixes typed and scanned pages only gets OCR where it's needed.
OCR in your browser
The whole recognition process runs on your device. Your document never leaves it and nothing is stored. The first time you use a language, your browser downloads its recognition data from ConvertirDocs. That's several MB, and it's only language data, never your document. Long documents take longer, and a progress bar shows you each page as it's processed.
It's free, with no account and no limit on use. If your PDF is protected with a password, remove it first with “Unlock PDF”.