Best way to search across multiple PDF documents

I have four book-sized pdf documents with OCR in Files on my iPad Pro.

What is the best way to search for specific words at the same time across the four PDFs?

Is it to keep them in Files, or Apple Books or the Kindle app or fourth way?

1 Like

DEVONthink and DEVONthink To Go love this sort of thing. There may be cheaper solutions too. I searched for “Parietal” in my databases and got these 500+ hits instantly.


Thanks @JohnAtl!

Ouch at $20. I have of course heard about DevonThink, I’ll give the iOS version a spin :blush:

Hi John

I just downloaded DevonThink for the iPad. How exactly do I get my books in PDF format into it?

I usually go into the pdf on my iPad and share it intoDevonrhink - worksgreat.


I always use it in conjunction with the desktop app, so I’m not sure. Sounds like @Sven has the answer though.

Hmm I’m not sure DevonThink for iPad is doing what I’m looking for.

I imported the four books, which are in OCR’ered PDFs, into DevonThink.

Then I did a search for a word, which I know should show up in more than one of the PDFs.

But I can only see that it is mentioned in all four books, but not which pages. So I still have to go back to the individual pdf and search inside of it, which means that I can just as well use PDFExpert on the iPad.

Unless I’m missing something?

The Liquidtext app could work well in this context, possibly.

That said:

Are these 4 pdfs the same - are you constantly searching for different terms in the same 4 documents, or is this more of a once-off, that is occasionally required?
Secondly, is this purely to check their existence, or do you need to do something ‘meaningful’ with their being located - i.e, mark where they are relative to each other, or come back to them later, or link them to one another etc.?

No, they are four different books in pdf format. I will need it from time to time over the next few months to do quick searches for words and phrases inside all four documents at the same time, instead of having to go to each individual document and perform the same search.

This is just for having to search across all four PDFs at the same time and then locate where the word is and then be able to enter each document and read more about what it says about that concept. I hope that makes sense?

LiquidText will come close – but there might be other options out there.

Regardless, what could be done in LT is the following:

It has a feature called the “DocPane” (which might require an IAP to activate). This essentially allows one to have more than 1 PDF “active” at any given time – in other words, you ‘import’ different PDFs into the DocPane, which then allows one to jump very quickly between the different PDFs.
It also allows one to ‘draw’ live back-links between all the PDFs present within the DocPane – which is a particularly powerful feature if one needs to compare, and link between, multiple PDFs.

However, it also allows one to simultaneously ‘view’ more than 1 PDF at the same time.
What it does is split the view of the different PDFs up into however many PDFs from the DocPane you decide to make ‘active’… You can then scroll/interact with each PDF individually.

4 PDFs might become a bit cramped, though.
3 is passable on the 12.9" iPP, but it works best with only 2 being active at any given time.

However, for your purposes – if you have 4 PDFs added to the DocPane (as opposed to having them ‘active’ so that one sees them at the same time), and you then trigger a search for a term in PDF 1 – it highlights where that term is present.
But when you then tap on PDF2 in the DocPane view, it automatically switches, and shows you where that same term is present in PDF2, and using the “previous/next” buttons, you can quickly jump between all the terms.
This would then apply equally as you invoke PDF3, PDF4, PDF5 etc.

So your scenario could see you add PDFs 1-4 to a single DocPane, and then invoke the search function in any one of them – and then use the DocPane side-bar to quickly jump between those different PDFs, with it then retaining the ‘search query’, and allowing you to quickly see where that term appears in each PDF…

Not sure if the above makes sense (given how I have tried to explain this in the absence of screenshots) – or if it might be the answer you are looking for, but figured I would mention it!


Depending on size, another option might be to append the PDFs into one, then search using pdf Expert or something similar.

1 Like