Selfhosted

The OCR thing is it's own task but for just searching a string in PDFs, pdfgrep is very good.

pdfgrep -ri CoolNumber69 /path/to/folder

For the OCR process you can probably wrangle up a simple bash pipeline with ocrmypdf and just let it run in the background once until all your PDFs have a text layer.

With that tool it should be doable with something like a simple while loop:

find . -type f -name '*.pdf' -print0 |
    while IFS= read -r -d '' file; do
        echo "Processing $file ..."
        ocrmypdf "$file" "$file"
        # ocrmypdf "$file" "${file%.pdf}_ocr.pdf"   # if you want a new file instead of overwriting the old
    done

If you need additional languages or other options you'll have to delve a little deeper into the ocrmypdf documentation but this should be enough duct tape to just whip up a full OCR cycle.

Try paperless-ngx. It can do OCR and has search.

You might want to check out Docspell - it's lighter than paperless-ngx but still handles PDF indexing and searching realy well, plus it can do basic OCR on those image-based PDFs without much setup.

@Darkassassin07 Did you already considered https://pdfgrep.org/?

With pdfgrep --ignore-case --recursive "text" **/*.pdf for example you can search a directory hierarchy of pdf files for "text".

In windows you may need to add an ifilter. Adobe’s is pretty good. Then windows search will be able to search contents.