About OCR PDF
OCR PDF turns a scanned, image-only PDF into a searchable one. It reads each page with on-device OCR and adds an invisible text layer behind the image — so you can select, copy and search the words, while the page still looks pixel-for-pixel identical. Pick up to three languages to match your document, and everything runs in your browser with no upload.
- No uploads
- Browser-only
- Works offline
- 100% free
How it works
- 1
Drop a scanned PDF
Best results come from image-only PDFs — photographed or scanned documents that have no text you can currently select.
- 2
Pick the OCR language(s)
Choose up to three languages that match the document. The first run downloads each language's data (about 5 MB) and caches it for next time.
- 3
Run OCR and download
Each page is rendered, recognised, and given an invisible text layer. The output looks the same but is now fully selectable and searchable.
OCR PDF, Scan to PDF and image OCR — which one you need
‘OCR’ shows up on three SnapToolz tools and they do genuinely different jobs. The deciding question is what you start with and what you want back — a searchable document, a fresh scan, or just the raw text copied out of a picture.
| You start with | You want | Use |
|---|---|---|
| A scanned image-only PDF | The same PDF, now searchable | OCR PDF (this tool) |
| A paper document + a camera | A new multi-page PDF | Scan to PDF, then OCR PDF |
| A photo or screenshot of text | The plain text copied out | Image OCR |
| A PDF you can already select text in | Nothing — it's already searchable | No OCR needed |
OCR PDF preserves the page image and hides the recognised text behind it; image OCR just returns the text. Scan to PDF creates the document that OCR PDF then makes searchable.
Getting the most accurate text layer
- Select only the languages actually present — each extra language slows recognition and can lower accuracy, since the engine weighs more character shapes per page.
- Feed it the cleanest scan you have: high contrast, straight, and at least 300 DPI. Faint, skewed or low-resolution pages produce a noisier text layer.
- The visible page is never altered, so any recognition errors live only in the hidden search layer — the document still looks perfect to a reader.
- First use of a language downloads roughly 5 MB of data, cached afterwards, so the first run is slower than the ones that follow.
- Once searchable, the PDF works with Compare PDFs and text extraction that need a real text layer to function.
Frequently asked questions about OCR PDF
Will OCR change how my document looks?
No. The original page image is left exactly as it was — OCR PDF adds the recognised text as an invisible layer positioned behind the visuals. Visually nothing changes; functionally, the text becomes selectable, copyable and searchable.
How many languages can I select, and does more help?
Up to three at once. Add languages only for scripts actually present in the document — each extra language slows recognition and can slightly reduce accuracy, because the engine has more character shapes to consider on every page.
My PDF already has selectable text — do I need this?
No. OCR is for image-only PDFs (scans and photos). If you can already select and copy the text, it has a text layer and running OCR would just add processing for no benefit. Use it precisely when copy-and-select does nothing.
How accurate is the recognised text?
Accuracy depends on the scan: clean, high-contrast, straight pages in a matched language read very well, while faint, skewed or low-resolution scans introduce errors. Because the visible image is untouched, any recognition mistakes only affect the hidden search layer, not what a reader sees.
Privacy, offline use, browser support, and pricing questions are answered on the site-wide FAQ.