Ctrl+F. Type your query. 'No results.' But the word is right there on the page in front of you.
The PDF has no text layer. The 'text' you're looking at is just an image of letters. The viewer's search has nothing to find.
What's actually going wrong
PDFs can hold two kinds of text: real vector text (what most modern documents have) and image-based text (what scans and some exports produce). Only vector text is searchable.
Your PDF was either scanned without OCR, exported from a tool that treats text as an image, or run through a compressor that flattened the text layer. The result looks identical, but the search box has nothing to grip.
The quick fix: OCR
Run the file through convert PDF to Word. Flint's OCR scans every page and generates a real text layer alongside the image. Open the Word document to confirm the recognition looks right, then convert back to PDF.
The new PDF looks identical to the old one but is fully searchable, copyable, and selectable. You can find any phrase in seconds.
If that didn't work
OCR accuracy depends on the source. Crisp 300dpi scans recognise nearly perfectly. Old faxes, low-res scans, or handwriting recognise poorly — better than nothing, but you'll see errors.
For large documents, OCR can take a minute or two. Don't cancel — Flint processes each page sequentially and the final output includes a complete text index.
For PDFs that have a text layer but search still doesn't work, the layer might be in a different language than your viewer's search defaults. Switch viewer language or use Flint's annotate PDF which handles multilingual search.
Prevent it next time
Set your scanner to OCR on capture. Most modern scanners and scanning apps include OCR options — turning it on means every scan is searchable from day one. When receiving PDFs, do a quick Ctrl+F test before filing them to confirm searchability.
FAQ
What is OCR exactly?
Optical Character Recognition reads images of text and generates digital text equivalents. The PDF still contains the image, but now also has an invisible text layer overlaid on it, which is what search and selection use.
Does OCR change how my PDF looks?
No. The visible content stays identical. OCR adds an invisible text layer behind the image. The file may grow slightly to hold the new text data, but visually it's unchanged.
Can OCR recognise handwriting?
Standard OCR handles printed text well but struggles with handwriting. Some specialised tools handle neat handwriting; most cursive or messy handwriting remains beyond reliable recognition.
Why is search slow in my large PDF?
Large unsearchable PDFs sometimes get slow real-time search because the viewer re-scans on each query. Once you add a real text layer via OCR, search is instant regardless of file size.
If Ctrl+F finds nothing, your PDF has no text. Run it through Flint's converter once and it's searchable forever.