Which app is best for a PDF viewer?

Last reviewed: September 23, 2026 · Markdown version

"Best PDF viewer" is four questions wearing one coat, and the honest first answer is that your phone already opens PDFs and most people need nothing else. The four jobs are: open one, annotate one, edit one, and find something across many. Different tools win each, and the fourth is the one nobody has installed anything for.

What you already have

On iPhone, Apple says that in the Files app "you can find and view your documents, images, and other files that you downloaded from the internet or your mail app" (Find your downloaded files on iPhone, read 23 September 2026), and that "You can open and save PDFs in the Books app that you receive in Mail, Messages, or other apps" (Read PDF documents in the Books app on iPhone, read 23 September 2026). On Android, Google states plainly what Files by Google is for — "Use Files by Google to free up space on your device and browse and share your files" — and that it "works on Android version 8.0 and up" (How to use Files by Google, read 23 September 2026); its help adds "You can directly open and edit PDF files in the Files by Google app" (Open, manage & edit PDFs in Files by Google, read 23 September 2026).

For reading one document, that is the end of the question. An app that only opens PDFs is not adding anything.

Job 2 — annotate

Highlighting, notes and signatures. The built-in apps cover the basics: in Books you "tap the Markup button to use the drawing and annotation tools" (Read PDF documents in the Books app on iPhone, read 23 September 2026), and Files by Google lists a pen and a highlighter among its annotating tools (Open, manage & edit PDFs in Files by Google, read 23 September 2026). A dedicated annotation app is worth trying when the marks have to be read in somebody else's software; test that round trip before relying on it.

Job 3 — edit and OCR

Changing the text itself, or turning a scan into selectable text. Acrobat is the reference implementation here: "All tools > Scan & OCR", then "In this file", and "Acrobat creates a searchable text layer in your PDF" (Recognize text in scanned documents, read 23 September 2026). This is desktop-shaped work, and Adobe's pricing page lists Acrobat Standard and Pro with monthly and annual subscription options (adobe.com/acrobat/pricing, read 23 September 2026). The exact Acrobat steps.

Job 4 — find something across many documents

This is the one the built-in tools only partly reach. On iPhone, Apple's Files help describes its search field as the way "To search for a file name" (Find files — Apple Support, read 23 September 2026). On Android, Files by Google's Smart Search can look for "Text from images and .pdf" where it is available (Search for a file, read 23 September 2026), but Google's page does not say whether a result tells you the page or shows the sentence. The question "which of my ninety PDFs mentions this policy number, and on what page" is a library question, and a reader is built around one document at a time.

How to pick, in one question

Ask what you did last time the PDF frustrated you. If you were squinting, you want a reader. If you were signing, an annotator. If you were retyping, an editor. If you were opening files one after another looking for a number — that is job four, and no amount of a better reader fixes it.

Where DocFind fits

DocFind is built for job four only, and it is worth being clear that it is not trying to be your reader, your annotator or your editor. It indexes many PDFs and searches them together: results show the file, the page and the surrounding text, and tapping one opens that PDF at that exact page with your keywords highlighted. Scanned PDFs are read on the device first and then searched like any other document, with matches found that way labelled as such, and any page it could not make searchable reported rather than quietly dropped.

The limits, stated: PDFs only — not Word, Excel or plain text. Matching is exact, so "running" will not find "run". There is no cloud and no account: the index is built on the phone and stays there. Free tier: one library of up to 25 documents, 10 scanned pages and 10 exports every month, with unlimited keywords and unlimited results. There is a demo with sample documents and no setup if you want to see the result view before deciding.