15 Best Free PDF Reader Apps for Android in 2025 - Ad-Free [Updated].

Hey PDF fans!
Feeling lost in a sea of confusing apps just to read a simple document? You're not alone — and we’re here to help!

In this updated 2025 guide, we’ll walk you through the 15 best free PDF reader apps for Android that are not only ad-free and secure, but also super user-friendly. Whether you're reviewing lecture notes, reading eBooks, or managing office files on the go, this list has something for everyone.

💡 Think of it as your personalized roadmap to PDF freedom — with fast-loading, clutter-free apps that respect your privacy and don’t bombard you with annoying ads.

Let’s find the perfect PDF reader for your Android device in 2025 — starting now.

15 Best Free PDF Reader Apps for Android in 2025 (Ad-Free & Safe)

1. Google PDF Viewer

Google PDF Viewer remains one of the most reliable and lightweight tools for reading PDFs on Android in 2025. It’s developed by Google and often comes pre-installed on many Android devices. With seamless Google Drive integration and a distraction-free interface, it’s perfect for users who want a simple, secure PDF reader without extra features or ads.

For managing your files more efficiently, you might also find how to clean up junk files using Windows tools.

Key Features of Google PDF Viewer

• Clean & Minimal Interface: Simple design focused entirely on readability without unnecessary menus.
• Fast & Reliable Performance: Loads even large documents quickly with no lag, thanks to Google’s backend optimization.
• Google Drive Integration: Open PDFs directly from Drive without downloading them — ideal for saving space.
• Offline Access: Download files for offline reading — great for flights or areas with poor connectivity.
• Basic Search & Navigation: Easily search inside documents, jump to specific pages, and zoom in/out.

Pros

• Lightweight and fast
• No ads or bloatware
• Integrated with Google ecosystem
• No setup required (usually pre-installed)

Cons

• No annotation or editing features
• Limited customization options (e.g., dark mode, page styles)

Best For

Users who want a fast, reliable, no-frills PDF reader that works seamlessly with Google Drive.

Verdict

Google PDF Viewer is best suited for those who value speed, simplicity, and security. If you just want to open and read PDFs without being interrupted by ads or bloated toolbars, this app gets the job done — and it does it well.

2. Adobe Acrobat Reader: Edit PDF App

Adobe Acrobat Reader continues to be one of the most widely used and trusted PDF reader apps for Android in 2025. Backed by decades of leadership in PDF technology, it delivers unmatched document fidelity, annotation tools, and seamless cross-device support.

While it offers a feature-rich free version, some advanced tools (like editing and page reordering) require a paid upgrade. Still, its free tier is excellent for reading and basic interactions — all without ads.

Key Features of Adobe Acrobat Reader

• Comprehensive Viewing Tools: Zoom, pan, rotate, and search PDFs effortlessly with responsive controls.
• Annotation Capabilities: Highlight, underline, strike through, add sticky notes, and draw directly on your documents.
• Accessibility Support: Features like text-to-speech, reflow view, and color adjustments help visually impaired users navigate PDFs.
• Cross-Platform Syncing: Access your documents across Android, iOS, Windows, macOS, and web through Adobe Document Cloud.
• Offline Functionality: Read and annotate PDFs even when you’re offline — no internet required for core features.

Pros

• Powerful annotation and accessibility tools
• Clean interface with dark mode support
• Reliable rendering for complex files (forms, scanned docs)
• Adobe Cloud sync across devices

Cons

• Some editing features locked behind a paywall
• Slightly heavier than minimalist readers
• Sign-in required for full feature access

Best For

Students, professionals, and power users who want rich annotation tools and enterprise-level reliability.

Verdict

Adobe Acrobat Reader is a top-tier choice for anyone needing more than just basic reading. If you're looking for professional features, excellent document rendering, and robust cross-device syncing, Adobe delivers — even on its free version.

3. WPS Office – PDF, Word, Sheet, PPT

WPS Office is more than just a PDF reader — it’s a full office suite that lets you manage documents, spreadsheets, presentations, and PDFs all in one app. For users who want to read PDFs while also handling other file types on Android, WPS is a flexible and compact solution.

While it’s not as feature-rich as Adobe for PDF editing, it packs enough tools for basic markup, conversion, and security — with an intuitive interface and cloud support.

Key Features of WPS Office

• PDF Annotation Tools: Highlight text, add comments, and insert shapes or notes for easy reviewing and feedback.
• File Conversion Support: Convert PDFs into editable Word, Excel, or PowerPoint formats directly within the app.
• PDF Compression: Shrink large PDF files to make them easier to share or store.
• Password Protection: Encrypt sensitive PDFs with passwords for secure access.
• Digital Signature Support: Sign documents electronically — ideal for contracts and business use.

Pros

• All-in-one office suite (PDF + Word + Excel + PPT)
• Solid conversion tools for repurposing content
• Supports annotations and signatures
• Cloud storage integration (WPS Cloud, Dropbox, etc.)

Cons

• Contains optional ads (can be removed with upgrade)
• Some features are locked behind the premium version
• Slightly more complex UI than single-purpose readers

Best For

Users who want an all-in-one office suite that handles PDFs and office documents in one place.

Verdict

WPS Office is perfect for Android users who frequently work with multiple document formats. If you value convenience and need a multi-functional, lightweight app that reads PDFs and edits DOCX or XLSX files too — WPS is hard to beat. 

4. PDF Extra – PDF Editor & Scanner

PDF Extra is a powerful Android app that combines advanced PDF editing, mobile document scanning, and format conversion in a single, easy-to-use platform. With its intuitive design and business-ready features, it’s ideal for users who want a more capable PDF tool without needing a desktop solution.

While some premium tools require a subscription, the free version is ad-free and includes essential features for reading, scanning, and basic editing.

Key Features of PDF Extra

• Advanced Editing Tools: Edit existing text, images, and layout elements directly within the PDF, including interactive forms.
• Efficient Scanning: Use your phone’s camera to scan physical documents and save them as high-quality, searchable PDFs.
• Annotation and Collaboration: Add highlights, comments, shapes, and handwritten notes — perfect for reviewing and teamwork.
• Multi-Format Conversion: Convert PDFs to editable Word, Excel, and ePub formats for easier content repurposing.
• User-Friendly Interface: Clean, modern UI ensures quick access to editing, scanning, and viewing features without a steep learning curve.

Pros

• Great for editing text and scanned documents
• Built-in scanner with OCR (optical character recognition)
• Clean, responsive interface
• Reliable offline support

Cons

• Some advanced tools require a subscription
• Slightly heavier app size than minimalist readers
• Free version includes limited cloud access

Best For

Professionals, freelancers, or students who need scanning, editing, and format conversion in one sleek app.

Verdict

PDF Extra is ideal for users who want to do more than just read PDFs. Whether you're scanning contracts, editing resumes, or annotating eBooks, it brings desktop-grade PDF tools right to your Android device — all with a polished mobile experience.

5. Foxit PDF Editor

Foxit PDF Editor is a professional-grade yet lightweight PDF tool designed for both casual readers and advanced users. Known for its speed, clean UI, and collaboration tools, Foxit delivers a balance between powerful features and mobile efficiency — all while keeping your documents secure and ad-free.

Even in its free version, Foxit provides essential editing, signing, and annotation features, with premium upgrades unlocking advanced tools.

Key Features of Foxit PDF Editor

• Comprehensive Editing Tools: Edit text, images, and pages directly in PDFs. Supports form filling and advanced layout control.
• Real-Time Collaboration: Share documents, comment, and annotate together with teammates or clients via cloud-based workflows.
• Robust Security Options: Password-protect files, redact sensitive information, and enjoy private, ad-free usage.
• Mobile Productivity: Optimized for Android, Foxit lets you manage documents smoothly on the go with fast loading and minimal lag.
• Cloud Integration: Connect with Google Drive, OneDrive, Dropbox, and other cloud services for seamless file access and sharing.

Pros

• Fast and lightweight even on older Android devices
• Great editing and collaboration features
• Strong document protection options
• No ads in the free version

Cons

• Some advanced features (e.g., OCR, batch processing) require a subscription
• UI may feel technical for first-time users
• Limited template library compared to desktop version

Best For

Business professionals, students, and teams needing secure, mobile-friendly PDF editing and collaboration.

Verdict

Foxit PDF Editor brings the power of a desktop-grade PDF suite to your Android device. With its focus on performance, security, and collaboration, it's one of the best choices in 2025 for users who want more than just a basic reader — without sacrificing speed or usability.

6. PDF Editor – Edit Everything!

PDF Editor – Edit Everything! is a versatile and powerful PDF editing app that gives you comprehensive control over your documents. From direct text and image edits to annotations and form filling, it’s designed for users who need a flexible yet easy-to-use PDF editor on Android.

The app also focuses on accessibility and customization, making it suitable for diverse users, including those with specific reading needs.

Key Features of PDF Editor – Edit Everything!

• Comprehensive Editing: Edit text, add or replace images, modify page layouts, redact sensitive information, and more.
• Tailored Reading Experience: Adjust fonts, colors, and use text-to-speech features to personalize your PDF reading.
• Intuitive Interface: Clean, user-friendly design that ensures smooth navigation across Android devices.
• Accessibility Support: Compatible with screen readers and offers customizable options to support users with disabilities.
• Customization Tools: Create bookmarks, add annotations, and switch between viewing modes for optimal document interaction.
• Cloud and Platform Integration: Sync your work across devices and cloud services for easy access anytime, anywhere.

Pros

• All-in-one editing and reading customization
• Strong accessibility features
• Intuitive UI with smooth performance
• Supports a wide range of PDF workflows (personal & professional)

Cons

• Advanced features may require a subscription
• Some UI elements can feel overwhelming initially
• Limited offline cloud sync without upgrade

Best For

Users seeking a full-featured PDF editor with robust accessibility and customization options.

Verdict

PDF Editor – Edit Everything! stands out as a powerful, accessible, and flexible PDF tool for Android users who want full control over their documents. It’s ideal for both personal and professional use, especially if you value customizable reading and editing features.

7. PDF Viewer – PDF Reader

PDF Viewer – PDF Reader is a lightweight and straightforward PDF reading app for Android users who prioritize speed, simplicity, and offline access. It strips away complex features, offering a no-frills solution focused entirely on clean document viewing — ideal for casual users or low-spec devices.

Although it lacks advanced tools like annotation or editing, it performs exceptionally well for basic tasks such as reading, searching, and navigating through PDFs without ads or interruptions.

Key Features of PDF Viewer – PDF Reader

• Minimal Interface: Clean and uncluttered layout optimized for distraction-free reading
• Search & Page Navigation: Quickly find text and jump between pages with ease
• Zoom & Fit-to-Screen: Adjustable view options for enhanced readability
• Offline Access: Perfect for reading documents without an internet connectionLightweight Performance: Uses minimal storage and works smoothly on all Android devices

Pros

• Extremely easy to use
• Fast loading, even for large PDFs
• No ads or in-app distractions
• Great for basic reading needs

Cons

• No editing or annotation capabilities
• Lacks features like form filling or signing
• No built-in cloud sync or file conversion

Best For

Users who need a clean, ad-free PDF viewer that works reliably on any Android device, especially those looking to fix performance issues or app crashes on Android.

Verdict

If your primary need is simply reading PDFs without the bloat, PDF Viewer – PDF Reader is an excellent choice. It’s one of the best lightweight options for Android users who don’t need extras like editing or cloud sync — just a reliable tool that does the basics well.

8. PDF Reader App: Read All PDF

PDF Reader App: Read All PDF is a user-friendly PDF viewer designed for casual users who want a straightforward, no-fuss reading experience. It focuses on speed, ease of navigation, and essential customization features — making it a great option if you’re looking for something simple but effective.

This app doesn’t overwhelm with advanced editing tools like PDF Editor or cloud-heavy suites like WPS Office, but it shines in delivering smooth reading performance and convenient extras.

Key Features of PDF Reader App: Read All PDF

• Effortless PDF Opening: Instantly open PDFs without lag or loading delays — perfect for quick access to your documents.
• Intuitive Navigation: Swipe smoothly through pages, zoom in/out easily, and jump to any section with minimal effort.
• Customizable Viewing: Adjust brightness, font size, and text orientation to suit your reading preferences, including a night mode for low-light environments.
• Bookmarking: Mark important pages or sections for quick reference later.
• Offline Reading: Access your documents anytime, even without an internet connection — ideal for travel or areas with spotty service.
• Cloud Sync Support: Sync your PDFs across multiple devices, allowing seamless access similar to how to backup files.
• File Sharing: Share PDFs effortlessly through email, messaging apps, or social media platforms.

Pros

• Simple, clean interface with minimal learning curve
• Fast loading and smooth page transitions
• Useful customization options for comfortable reading
• Supports offline access and cloud syncing

Cons

• Lacks advanced editing or annotation tools found in apps like PDF Editor
• No built-in scanning or conversion features
• Limited to basic PDF viewing and sharing

Best For

Users who want a lightweight, easy-to-use PDF reader focused on fast access and comfortable reading — without the extra bells and whistles.

Verdict

If you need a reliable app to quickly open and read PDFs with useful customization and sharing options, PDF Reader App: Read All PDF offers a solid, distraction-free experience. It complements more powerful apps like Adobe Acrobat Reader and PDF Extra by focusing purely on smooth, straightforward PDF reading.

9. Fill & Sign PDF Form Signature 

Gone are the days of printing, signing, and scanning PDFs! With Fill & Sign PDF Form Signature, you can conveniently fill out and electronically sign forms directly on your device. This app saves time, reduces paper waste, and makes document processing seamless and secure.

This app is perfect for anyone who frequently handles PDF forms and needs a quick, reliable way to complete and sign them without printing.

Key Features of Fill & Sign PDF Form Signature

• Easy Form Filling: Quickly fill out PDF forms by tapping form fields and entering text or checkmarks.
• Multiple Signature Options: Draw your signature, type it, or upload an image to personalize your sign-off.
• Secure Signing: Protect your documents with encryption and password options to keep your data safe.
• Annotation Tools: Add notes, highlights, or stamps to your PDF forms if needed.
• Cloud Integration: Sync and save your signed forms across devices via popular cloud services.

Pros

• Streamlines the signing and form-filling process
• User-friendly and intuitive interface
• Secure with encryption and password protection
• Supports multiple signature methods

Cons

• Limited advanced editing tools compared to full PDF editors
• Some features may require paid upgrades
• Not ideal if you need complex PDF creation or heavy annotation

Best For

Users who want a fast, straightforward way to fill and sign PDF forms electronically — perfect for work, school, or personal use.

Verdict

Fill & Sign PDF Form Signature is a handy tool that replaces the old printing-and-scanning hassle. It’s a great complement to more powerful PDF apps, focusing on smooth and secure form handling.

10. PDF Expert - PDF Reader

PDF Expert is a powerful PDF file manager and reader designed for advanced users who need more than just basic viewing. It offers efficient ways to open, edit, annotate, and manage PDF documents with ease. The app supports sharing, page rearrangement, and renaming of PDFs, making it a versatile tool for handling documents professionally.

Though primarily popular on iOS and Mac, it offers a rich set of features that professionals appreciate for their workflow.

Key Features of PDF Expert - PDF Reader

• Extensive Annotation Tools: Highlight, underline, strikethrough, add text boxes, sticky notes, shapes, and freehand annotations.
• Advanced Markup Capabilities: Customize the size, color, and style of your annotations for better clarity and presentation.
• Collaboration Features: Leave comments and feedback to work asynchronously with others on shared documents.
• OCR Technology: Extract text from scanned PDFs to make documents searchable and editable.
• Cross-Platform Sync: Seamless file and annotation synchronization across devices via iCloud or proprietary sync service.
• Advanced File Management: Create folders, tag PDFs, and password-protect sensitive files.
• Cloud Storage Integration: Connect and manage files from Dropbox, Google Drive, and other cloud services.

Pros

• Powerful annotation and editing tools
• Smooth file organization and management
• Collaboration-friendly with commenting features
• OCR support enhances usability of scanned documents

Cons

• Limited availability on Android devices
• Some advanced features require a subscription
• Primarily optimized for iOS and macOS

Best For

Users looking for a professional-grade PDF tool with comprehensive annotation, editing, and file management — especially those in Apple’s ecosystem.

Verdict

PDF Expert - PDF Reader excels as a robust PDF solution for power users focused on detailed editing and document management. While Android users may need alternative apps, it remains a top choice for Mac and iOS users who want a feature-rich PDF experience.

11. Xodo PDF Reader & Editor Tool

Xodo provides a secure and synchronized file management solution that supports storage on Xodo Drive, Dropbox, Google Drive, and OneDrive. It offers a versatile platform for viewing, editing, converting, signing, redacting, compressing, and merging PDF files, ensuring accessibility and functionality anytime, anywhere.

Xodo is popular among Android users for its powerful features and ease of use.

Key Features of Xodo PDF Reader & Editor Tool

• PDF Editing: Create and directly edit PDFs with tools for flattening, compressing, merging, rotating, and splitting/extracting pages.
• Scan & Convert: Convert various file formats to PDF quickly. Includes a PDF scanner with OCR to make images and PDFs searchable.
• View & Print PDFs: Offers single and double-page viewing modes, Dark Mode, Reflow Reading Mode, multiple tabs, bookmarks, and printing capabilities.
• Annotate & Draw: Use markup tools, page arrangement options, scrolling mode, and stylus support for detailed annotation.
• Fill & Sign PDF Forms: Easily fill out, sign electronically, and share PDF forms, syncing with cloud storage.
• Store & Manage Securely: Built-in file manager with password protection, grid view mode, and secure organization of your PDF files.

Pros

• Rich feature set for editing, annotating, and managing PDFs
• Cloud synchronization with major storage providers
• User-friendly interface with stylus support
• Free to use with no intrusive ads

Cons

• Occasional minor bugs reported on some Android devices
• Advanced features could overwhelm casual users

Best For

Users who want a full-featured, free PDF editor and reader with robust annotation, scanning, and cloud syncing — especially on Android devices.

Verdict

Xodo PDF Reader & Editor Tool stands out as an all-in-one, reliable app for anyone needing comprehensive PDF management on Android. It balances power and usability, making it a top choice for students, professionals, and casual readers alike.

12. PDF Viewer Lite

PDF Viewer Lite is a free, ad-free, and lightweight app designed specifically for Android devices. It focuses on delivering a basic yet powerful experience for viewing, annotating, and managing PDFs. Despite its "Lite" name, it offers a surprising number of features tailored for casual users and those with limited storage space.

Key Features of PDF Viewer Lite

• Lightweight Champion: Small app size ensures smooth performance on older or low-storage devices without draining memory.
• Multi-Format Magic: Opens not only PDFs but also EPUB, TIFF, and XPS documents, making it versatile for different file types.
• Annotation Arsenal: Highlight, underline, and add text annotations easily to emphasize important information.
• Reading Nirvana: Smooth scrolling, customizable zoom levels, and multiple page layouts offer a comfortable reading experience.
• Document Management Dynamo: Organize PDFs in a dedicated library with easy access and password protection for added security.

Pros

• Free and ad-free, with a clean, simple interface
• Runs smoothly even on older Android devices
• Supports multiple document formats beyond PDF
• Basic annotation tools for essential markup

Cons

• Lacks advanced editing or form-filling features
• Limited cloud integration options
• Best suited for casual readers rather than power users

Best For

Android users looking for a lightweight, straightforward PDF viewer with essential annotation and document management capabilities — ideal for devices with limited resources.

Verdict

PDF Viewer Lite is an excellent choice for Android users who want a no-nonsense, efficient PDF app that respects device limitations without compromising on core reading and annotation features.

13. Pdf Reader: Pdf Viewer

This free PDF Reader app by GameLoX offers basic features for viewing, managing, and interacting with PDFs on Android devices. It has a simple interface and small app size, making it suitable for casual users and those with limited storage space.

Best Features Of PDF Reader are:

1. Seamless Reading Experience: The app prioritizes a smooth reading experience with features like quick opening, smooth scrolling, and customizable zoom levels.
2. Essential Management Tools: Organize your PDFs in a dedicated library, search for specific documents, and access them easily with a simple tap.
3. Basic Annotation Options: Highlight important text, add notes, and draw on PDFs to enhance comprehension and reference key information.
4. Night Mode: Read comfortably in low-light environments with the adjustable night mode feature, protecting your eyes and reducing strain.
5. Offline Access: Read your PDFs even without an internet connection, making it convenient for travel or situations with limited internet access.

14. Simple PDF Reader - 2024

Simple PDF Reader - 2024 is a free PDF reader app that offers a self-proclaimed "simple X Apps" approach to viewing and managing PDFs on Android devices. It prioritizes a minimalistic interface and basic functionalities, making it potentially suitable for users who want a no-frills PDF experience.

Key Features of Pdf Reader: Pdf Viewer

• Seamless Reading Experience: Quick opening, smooth scrolling, and customizable zoom levels for comfortable reading.
• Essential Management Tools: Organize your PDFs in a dedicated library, easily search and access documents with a simple tap.
• Basic Annotation Options: Highlight text, add notes, and draw on PDFs to improve comprehension and reference.
• Night Mode: Adjustable night mode for comfortable reading in low-light conditions, reducing eye strain.
• Offline Access: Read PDFs anytime without needing an internet connection — perfect for travel or limited connectivity.

Pros

• Lightweight with a clean, user-friendly interface
• Good for casual PDF reading and basic annotations
• Supports night mode for eye comfort
• Works offline for uninterrupted access

Cons

• Lacks advanced editing or signing features
• Minimal cloud integration
• Limited to basic PDF functionality

Best For

Android users who want a straightforward, no-frills PDF reader with essential annotation features and offline support.

Verdict

Pdf Reader: Pdf Viewer is a solid choice for casual Android users looking for a simple, reliable app to read, organize, and lightly annotate PDFs without the bulk of more complex apps.

15. MuPDF Viewer

MuPDF Viewer isn't just your average PDF reader — it's a lightweight powerhouse known for its blazing-fast performance and minimal footprint. Perfect for users who prioritize speed, simplicity, and open-source efficiency, MuPDF is ideal for both casual and technical users on Android.

Key Features of MuPDF Viewer

• Tiny Footprint: Minimal in size, MuPDF is ideal for devices with limited storage — it installs quickly and takes up very little space.
• Minimal Resource Consumption: Runs effortlessly on older or low-powered Android devices without lags or slowdowns.
• Lightning-Fast Rendering: Pages load instantly, delivering a fluid and uninterrupted reading experience even with large files.
• Essential Functionality: Offers all the core features you need — zoom, pan, text search, bookmarks, and basic navigation.
• Annotation Support: Highlight, annotate, and add notes directly within your PDF files to customize your reading.
• Multi-Format Compatibility: Besides PDFs, MuPDF also supports formats like XPS, OpenXPS, CBZ, and ePUB for extended usability.
• Free and Open-Source: 100% free with source code available — a great option for developers or those who prefer open-source solutions.

Pros

• Extremely fast and efficient
• Very small app size — ideal for limited storage
• No ads, completely free and open-source
• Supports multiple file formats beyond PDF

Cons

• Basic UI - not as modern or polished as some competitors
• Limited advanced features (e.g., no editing or digital signatures)
• Might not appeal to users looking for a visually rich interface

Best For

Users who need a minimal, fast, and efficient PDF reader — especially useful for students, developers, or those with low-storage Android phones.

Verdict

MuPDF Viewer is a no-frills, high-performance solution for reading PDFs and other document formats on Android. If you want something fast, lightweight, and reliable without the extra bloat, MuPDF delivers exactly that.

Conclusion

In a world overflowing with digital documents, finding the perfect PDF reader for Android can feel like stumbling upon hidden treasure. From the minimalist efficiency of Google PDF Viewer, the trusted performance of Adobe Acrobat Reader, to the all-in-one capabilities of WPS Office, each app on this list brings something valuable to the table.

Whether you're a student highlighting notes, a night owl who prefers reading in dark mode, or just someone who wants an ad-free, lightweight experience, there’s a reader tailored to your needs.

Remember, it's not just about opening PDFs — it's about how seamlessly, securely, and comfortably you can interact with them. Take the time to explore these top 15 apps, and find the one that suits your style. Once you do, it’ll be more than an app — it’ll be your go-to companion for navigating the world of documents on the go.

Frequently Asked Questions (FAQs):

Which is the best ad-free PDF reader app for Android in 2025?

MuPDF Viewer, PDF Viewer Lite, and Google PDF Viewer are top ad-free options with great performance and privacy.

Can I edit PDFs using free Android apps?

Yes! Apps like Xodo, PDF Extra, and Foxit allow basic to advanced PDF editing without needing a paid plan.

Is there a PDF reader that works well offline?

Yes, most apps like Adobe Reader, PDF Extra, and PDF Viewer – PDF Reader offer full offline functionality.

Which PDF reader is best for filling and signing forms?

Use Fill & Sign PDF Form Signature or Adobe Reader — both support electronic form filling and digital signatures.

What’s the best lightweight PDF reader for older phones?

MuPDF Viewer and PDF Viewer Lite are extremely fast and light, making them ideal for low-storage or older devices.