This does work impressively fast until you realise that it isn't doing any OCR, as parent comment points out.

The site also throws up a certificate error which might make some people nervous; "Technical Details: pdftotext.org uses an invalid security certificate. The certificate is only valid for the following names: www.github.com, .github.com, .github.io, *.githubusercontent.com "

I think if you put a note on the site explaining what you are trying to do [practice running microsites on the cheap etc] that visitors would be reassured.