A good free PDF reader should make long documents comfortable to read on a phone or tablet.
Almost every important document still arrives as a PDF, from school assignments and job contracts to boarding passes, bank statements, and instruction manuals.
A good reader turns those files into something you can actually use on a small screen, with clear text, fast search, and tools for highlighting, signing, and sharing.
The best free apps below cover Android and iPhone without forcing you to pay just to open a file.
Choosing the right app depends less on brand names and more on what you do with documents every day, because a student marking up lecture slides needs different tools from someone who only signs one contract a month.
This guide compares six real, widely available apps, explains what is genuinely free in each one, and shows where the paywall starts so you can pick with confidence.
Best Picks at a Glance
Adobe Acrobat Reader — best overall free reader.
It opens almost any PDF reliably, supports highlights, comments, form filling, and signing for free, and works the same way on Android and iPhone.
Editing the text inside a PDF, converting files, and combining documents require a paid subscription, but everyday reading and signing do not.
Xodo PDF Reader & Editor — best free annotation toolkit. Xodo combines fast viewing with highlights, freehand drawing, form filling, signatures, and cloud sync with Google Drive, Dropbox, and OneDrive.
Some advanced tools, such as redaction and OCR options, sit behind a paid subscription, so check the current plan before relying on them.
Foxit PDF Reader — best lightweight alternative to Adobe.
Foxit opens files quickly, offers night mode and text reflow for small screens, and covers highlights, comments, form filling, and signing in its free version.
Working with XFA forms requires a subscription, while standard AcroForms remain free according to Foxit documentation.
Apple Books — best free option already on iPhone.
Apple Books is preinstalled on iPhone and iPad, opens PDFs shared from Mail, Messages, and other apps, and adds markup tools, bookmarks, search, and sharing without any extra download.
It is the simplest choice for iPhone owners who mainly read and lightly mark up documents.
Google Drive — best for files you already store in the cloud.
The free Google Drive app includes a built-in PDF viewer that lets you find, select, and copy text without opening another app, and it makes searching across your stored files straightforward.
It is a viewer first, so heavy annotation work is better done in a dedicated reader.
MuPDF — best minimal, open-source reader.
MuPDF is a free and open-source viewer focused on speed, small size, and clean rendering, with support for PDF, XPS, and EPUB files on Android and iOS.
It suits readers who want a fast, distraction-free viewer and do not need cloud storage, collaboration, or a large editing toolkit.
1. Adobe Acrobat Reader
Adobe Acrobat Reader is the reference point for PDF software because Adobe created the PDF format, and that history shows in its compatibility with complex files, forms, and signatures.
The free mobile app lets you view, share, annotate, add comments, and sign documents on Android and iPhone, and you can store files online and continue reading on another device.
Its Liquid Mode reflows suitable documents for easier reading on a phone, while search, zoom, and continuous scrolling cover the basics well.
Free features include sticky notes, highlights, and comments, plus Fill and Sign for filling in forms and adding a signature with a finger or stylus.
Editing text and images directly inside a PDF, converting PDFs to and from Office formats, combining documents, and using the AI Assistant are paid features, so treat Acrobat Reader as a strong free reader rather than a full editor.
That split is actually good news for most users, because the tasks people do most often cost nothing.
Pros:- Excellent compatibility with complex PDFs and forms
- Free highlights, comments, form filling, and signing
- Liquid Mode for easier phone reading
- Available on Android and iPhone, with cloud storage
Verdict: Start here if you want one dependable free reader that handles almost anything, and only consider paying if you regularly edit PDF text or convert files.
2. Xodo PDF Reader & Editor
Xodo has built its reputation on packing a large annotation toolkit into a free mobile app, and it remains one of the most capable free options for students and office workers.
You can read, annotate, sign, and share PDFs, fill in forms, and sync your edits back to Google Drive, Dropbox, and OneDrive, which keeps your documents consistent across devices.
It also supports night mode, bookmarks, full-text search, page thumbnails for reordering or deleting pages, and stylus input on supported devices.
The free version covers the core reading and annotation work that most people need, including highlights, underlines, freehand drawing, shapes, and saved signatures for reuse.
Advanced features such as redaction, OCR for scanned documents, and some compression and conversion options are tied to a paid subscription, and Xodo has introduced lower-cost subscription tiers over time.
Because Xodo changes its plans from time to time, it is worth checking the current free and paid split inside the app before starting a large project.
Pros:- Strong free annotation tools, including highlights, drawing, and shapes
- Form filling and reusable signatures
- Sync with Google Drive, Dropbox, and OneDrive
- Night mode, bookmarks, and full-text search
Verdict: Choose Xodo if you annotate heavily and want cloud sync without paying, and accept that a few advanced tools may require a subscription later.
3. Foxit PDF Reader
Foxit PDF Reader is a fast, lightweight alternative that has been popular for years with readers who want Adobe-level basics without a heavy app.
The free mobile version opens PDFs quickly, supports single-page and continuous layouts, search, bookmarks, and thumbnails, and adds text reflow to fit prose into a single mobile-width column.
Night mode, zoom controls, rotation, and background colour options make long reading sessions easier on a phone screen.
Annotation is well covered for free, with highlights, underlining, sticky notes, drawing, and comment threads, plus form filling and signing for everyday documents.
Foxit documentation states that working with standard AcroForms is free in the mobile reader, while XFA forms require a subscription, which is an important distinction for anyone handling government or corporate forms.
Full text editing, OCR conversion, and the most advanced features belong to the paid Foxit PDF Editor rather than the free reader.
Pros:- Fast and lightweight, even on older phones
- Text reflow and night mode for comfortable phone reading
- Free highlights, notes, form filling, and signing
- Available on Android, iPhone, Windows, macOS, and Linux
Verdict: Pick Foxit if you value speed and clean mobile reading, and keep Adobe or Xodo as a backup for unusual forms or heavy editing work.
4. Apple Books
Apple Books is easy to overlook because it arrives preinstalled on iPhone and iPad, but it is a genuinely useful free PDF reader for Apple users.
You can open and save PDFs received in Mail, Messages, or other apps, then read them in your Books library, search inside a document, add bookmarks, and share or print the file.
Apple Support also describes markup tools for PDFs in Books, including drawing and annotation tools reached from the top of the screen while reading.
For books and text-based documents, Apple Books supports highlights, underlining, and notes, and you can share those highlights and notes with others or search the text for a word or phrase.
The trade-off is that Apple Books is a reading app first, not a document editor, so it will not replace a full PDF editor for merging files, redacting text, or converting formats.
For iPhone owners who mainly read reports, ebooks, and manuals, however, it removes the need to install anything at all.
Pros:- Free and preinstalled on iPhone and iPad
- Simple PDF saving from Mail, Messages, and other apps
- Markup tools, bookmarks, search, and sharing
- Highlights and notes for reading-focused documents
Verdict: Use Apple Books first on iPhone if your needs are mostly reading and light markup, and add Xodo or Adobe only when you need stronger forms or editing tools.
5. Google Drive
Google Drive is not a dedicated PDF editor, but it deserves a place on this list because so many PDFs already live there, and its built-in viewer removes friction.
The free Drive app for Android and iPhone lets you store, search, share, and preview PDFs, and Google has described its PDF viewer as a way to find, select, and copy text in PDFs without launching another app.
Drive search also covers file titles and content you have permission to access, which helps when you remember a phrase but not a filename.
Sharing is the other strength, since you can send a file or a link, control who can view it, and add a message for collaborators when sharing from Drive.
The limitation is annotation depth, because Drive is built for storage and preview rather than detailed markup, so highlighting, drawing, and form workflows are better handled after opening the file in Acrobat Reader, Xodo, or Foxit.
Think of Drive as your free PDF library and quick viewer, with a dedicated reader one tap away when work gets serious.
Pros:- Free viewer built into an app many people already use
- Find, select, and copy text inside PDFs
- Strong search across stored files and easy sharing
- Available on Android and iPhone with cloud sync
Verdict: Keep Google Drive as your storage and quick-view tool, and pair it with a dedicated reader whenever you need to annotate, sign, or fill in forms properly.
6. MuPDF
MuPDF takes the opposite approach from the big-brand readers by focusing on speed, small size, and accurate rendering above all else.
It is a free and open-source framework and viewer written in C, developed by Artifex Software, and its stated focus is fast, high-quality, anti-aliased rendering with a small code footprint.
The viewer supports PDF, XPS, and EPUB files, along with text search, table-of-contents navigation, and hyperlinks, and it runs on Android and iOS as well as desktop systems.
Mobile versions of MuPDF support annotation and form filling, including highlight, underline, strike-out, and ink annotations, but the interface is deliberately minimal compared with Xodo or Adobe.
That minimalism is the point for readers who dislike clutter, upsell prompts, and large downloads, yet it also means you should not expect built-in cloud storage, collaboration, or conversion tools.
MuPDF is best seen as a dependable, no-nonsense viewer for people who value performance and simplicity over a long feature list.
Pros:- Completely free and open-source, with a tiny footprint
- Very fast rendering, even for large or complex documents
- Supports PDF, XPS, and EPUB files
- Search, outlines, and basic annotation and form filling on mobile
Verdict: Try MuPDF if you want a fast, private, distraction-free reader and you are happy to live without cloud sync and advanced editing features.
Comparison Table
| App | Platforms | Best free strengths | What usually costs extra |
|---|---|---|---|
| Adobe Acrobat Reader | Android, iPhone | Viewing, highlights, comments, form filling, signing | Editing PDF text, conversion, combining files, AI Assistant |
| Xodo PDF Reader & Editor | Android, iPhone | Annotation, form filling, signatures, cloud sync | Redaction, OCR, some compression and conversion tools |
| Foxit PDF Reader | Android, iPhone | Fast reading, reflow, night mode, annotation, signing | XFA forms, full text editing, OCR, advanced Editor features |
| Apple Books | iPhone, iPad | Reading, markup, bookmarks, search, sharing | Full editing, merging, redaction, conversion (not its focus) |
| Google Drive | Android, iPhone | Storage, search, preview, text selection, sharing | Deep annotation and editing (use a dedicated reader) |
| MuPDF | Android, iPhone | Fast, minimal, open-source viewing and basic markup | Cloud sync, collaboration, conversion (not included) |
How to Choose the Right Free PDF Reader
Start by listing the three things you do most often with PDFs, because that short list will eliminate most apps faster than any feature table can.
If your list is mostly reading and occasional signing, Apple Books on iPhone or Google Drive plus one dedicated reader will cover you without any cost.
If your list includes daily highlighting, comments, and form filling, Adobe Acrobat Reader, Xodo, or Foxit will save you far more time than a basic viewer.
Next, check how the app handles your files when you are offline, since a reader that needs a constant connection is frustrating on a train, a plane, or a campus with weak Wi-Fi.
Download a test PDF, turn on airplane mode, and confirm that you can still open it, search it, and save your highlights before you commit to the app.
Also confirm that your annotations actually stay in the file when you share it, because some reading apps keep notes inside the app rather than writing them into the PDF itself.
Finally, read the free-versus-paid split inside the app before you need a feature urgently, especially for signatures, form filling, and scanned documents.
Free tiers change over time, and a tool that was free last year may now sit behind a subscription, so a quick check today avoids a surprise before a deadline.
The safest approach is to keep two readers installed: one simple viewer for fast reading and one stronger annotator for work that matters.
Frequently Asked Questions
Do I really need a PDF reader app if my phone already opens PDFs?
Your phone can usually open a PDF in a browser, mail app, or file manager, but a dedicated reader adds search, bookmarks, highlights, form filling, and signing in one place.
Those tools matter as soon as you need to find a clause, mark up a report, or return a signed form without printing anything.
A dedicated app also remembers your place and keeps your files organised better than a one-off preview.
Which free PDF reader is best for students?
Xodo and Adobe Acrobat Reader are strong student picks because both offer free highlights, comments, and form tools that work well for lecture slides and assignments.
Xodo adds cloud sync with Google Drive, Dropbox, and OneDrive, which helps when coursework moves between a phone, a tablet, and a computer.
Foxit is another good choice for students with older phones, thanks to its lightweight design and text reflow for small screens.
Can I sign a PDF for free on Android and iPhone?
Yes, you can sign PDFs for free in Adobe Acrobat Reader, Xodo, and Foxit, all of which let you draw or save a signature and place it on a document.
Apple Books also offers markup and signature tools for PDFs on iPhone, which covers simple signing without installing another app.
For legally sensitive contracts, always check whether the recipient requires a certified digital signature, since a drawn signature and a certificate-based signature are not the same thing.
Are free PDF readers safe for sensitive documents?
Free readers from established developers are generally safe for everyday documents, but you should still avoid uploading sensitive files to unknown online tools or granting unnecessary permissions.
Keep confidential PDFs on your device or in a trusted cloud account, use the app store version of the reader, and check what the app syncs before enabling cloud backup.
For highly sensitive work, a minimal offline viewer such as MuPDF can reduce exposure, although it will not replace proper document security practices.
Why do some free PDF apps still ask me to pay?
Most free PDF readers follow a freemium model, where viewing, basic annotation, and signing are free while editing, conversion, OCR, and AI tools fund development through subscriptions.
That model is normal and not a warning sign by itself, provided the free features genuinely cover your needs without a trial countdown.
If an app blocks basic reading or signing behind payment, switch to one of the readers above, because those core tasks should not require a subscription.
For most people, the smart starting point is Adobe Acrobat Reader for reliability, Xodo for annotation, or Apple Books on iPhone for simplicity, with Google Drive handling storage and quick previews.
Try two of them with a real document from your own work or study, keep the one that feels fastest, and delete the rest so your phone stays uncluttered.
A free reader should remove friction from documents, not add another subscription to manage, and all six apps above do that job well in their own way.