Your phone is often the fastest device in your hand when a PDF needs immediate attention — a contract that just arrived, a boarding pass that needs to be shared, an invoice that needs signing before a deadline. But most people use maybe 10% of what mobile PDF workflows can do.
This guide covers the best practices for viewing, annotating, signing, converting, and sharing PDFs on iOS and Android — without needing to install bloated apps.
Best PDF Viewers for Mobile
📱 iOS (iPhone & iPad)
- Files app (built-in) — tap any PDF to open instantly. Supports markup, search, and sharing.
- Safari — opens PDFs inline with pinch-to-zoom and search (⌘+F on iPad with keyboard).
- Books app — excellent for long documents with bookmarks and night mode.
- Adobe Acrobat (free tier) — best for annotation and form filling.
🤖 Android
- Chrome browser — opens PDFs natively with search and share.
- Google Drive — tap any PDF to view with annotation tools built in.
- Adobe Acrobat (free tier) — full-featured, best for forms and signatures.
- Samsung My Files (Samsung devices) — built-in PDF viewer with decent annotation tools.
6 Essential Mobile PDF Tips
Search inside PDFs on mobile
In most mobile PDF viewers, tap the three-dot menu → Find / Search. In Chrome on Android, tap ⋮ → Find in page. In Safari on iPhone, tap the AA icon → Find on Page.
Annotate without an app on iOS
Open a PDF in Files app → tap the pen icon (top right) to access Apple's Markup tool. Draw, highlight, and add text directly on the PDF, then save or share.
Fill and sign on iOS
In Mail or Files, tap a PDF with form fields → iOS recognises fillable areas automatically. Sign with your finger using Markup's signature feature. Available without any extra app.
Share directly from the PDF viewer
In any PDF viewer, use the Share sheet (iOS) or Share button (Android) to send via AirDrop, Messages, WhatsApp, email, or directly save to cloud storage.
Scan a document as PDF on iPhone
Open Notes → new note → camera icon → Scan Documents. iOS scans, straightens, and exports a multi-page PDF of any physical document or receipt in seconds.
Compress a PDF before emailing on mobile
Open pdfsizereducer.com/tools/compress-pdf in Safari or Chrome, upload the PDF from your Files/Drive, compress it, and share the result — all without installing an app.
Using PDF Size Reducer on Mobile
Every PDF Size Reducer tool is fully responsive and touch-optimised. Here's how to use the most common tools from your phone:
Compress a PDF on iPhone
Open Safari → go to pdfsizereducer.com/tools/compress-pdf → tap the upload zone → select from Files or Photos → choose a preset → tap Compress → tap Download → save to Files or share directly.
Merge PDFs on Android
Open Chrome → go to pdfsizereducer.com/tools/merge-pdf → tap Upload → select your PDFs from Google Drive or local storage → reorder by dragging → tap Merge → download the result.
All PDF tools work on mobile
Compress, merge, split, protect — fully touch-optimised and free.
📱 Open PDF Tools on MobileFrequently Asked Questions
Share this guide