iPhone handles PDFs better than most people realise. Between the Files app, the Markup tool, and a browser-based toolkit, you can do almost everything you would do on a computer without installing a single app. This guide covers the full workflow: opening PDFs, saving them, editing and annotating, signing, compressing, merging, and converting.
Opening PDFs on iPhone
Safari opens PDFs directly, tap a PDF link in Safari and it opens in the browser with a bar at the top offering options to share or open in another app. The built-in PDF viewer lets you zoom, scroll, and search text within the document.
The Files app also opens PDFs, and typically offers more options. Long-press a PDF in Files to get Quick Actions including markup, printing, and copy. Tap a PDF to open it in the full-screen viewer, which includes the Markup tools.
Email attachments and iMessage attachments open in their respective apps' built-in viewers. From there, tap the Share button to pass the file to Files, Books (Apple's PDF reading app), or any other app on your phone.
Saving PDFs to iPhone
When you encounter a PDF you want to keep, tapping Share and choosing Save to Files is the standard route. Choose between iCloud Drive (synced across devices) or On My iPhone (local only). For documents you might need on other devices, like a job offer letter or a tax return, iCloud Drive is the better choice. For temporary files you will process and discard, local storage avoids syncing overhead.
The Books app (formerly iBooks) is another saving option, especially useful for documents you want to read offline. Books keeps a local copy and displays it in a reading-optimised layout. The trade-off is that Books does not appear in the Files app, so you cannot easily use the file in other workflows from there.
Annotating and marking up PDFs
iOS Markup is surprisingly capable. To access it, open a PDF in Files, tap the Markup icon (the pencil icon in the top-right corner of the viewer), and you get:
- Drawing tools: pen, pencil, highlighter, ruler
- Text boxes: type text anywhere on the page
- Shapes: circles, rectangles, arrows, speech bubbles
- Signature field: capture and reuse a signature
- Eraser: correct mistakes
Markup annotations are embedded into the PDF as you work. When you share or save the marked-up file, the annotations are part of the document. This is useful for reviewing contracts, annotating invoices, or highlighting text in a report.
Signing a PDF on iPhone without printing
Markup includes a signature tool. Tap the + button in Markup and choose Signature. You can draw your signature with your finger (or Apple Pencil on supported models) and save it for reuse. Once saved, tap the signature to place it anywhere on the page and resize it by dragging the handles.
For more complex signing scenarios, multiple signature fields, date stamps, initials boxes, PDFWhisk's sign PDF tool in Safari handles these in the browser without uploading the document. This is particularly useful for NDA agreements, contractor terms, or any document where you want to be certain the file does not pass through a third-party server.
Compressing a PDF on iPhone
The most common mobile PDF problem: a document that is too large to email or upload. iOS does not have a built-in compressor, but PDFWhisk's compressor runs in Safari and processes the file on your device. Open the compressor, tap to select your PDF from Files, choose a target size (5MB is practical for most email situations), and download the result. The whole process takes under thirty seconds for typical documents.
Common situations where you will need this:
- Job application portals with a 2MB or 5MB PDF size limit
- Gmail or Outlook attachment limits (25MB and 20MB respectively, but many recipients' mail servers are more restrictive)
- WhatsApp, which imposes its own file size limits on document sharing
- Government portals for benefits, visas, or tax returns that typically cap uploads at 5MB or 10MB
Merging multiple PDFs on iPhone
Merging two PDFs into one is not something iOS handles natively. The Files app can preview PDFs but cannot merge them. PDFWhisk's merge tool in Safari does this without an app: open the tool, select multiple PDFs from Files, reorder them by dragging, and download the merged file.
A common scenario where merging is useful on mobile: you receive several separate PDF attachments in an email, a cover letter, a CV, and references, and need to submit them as one file to a portal. Merge them in Safari, download the combined PDF, and upload from Files.
Splitting a PDF on iPhone
Splitting is the reverse: taking one PDF and extracting specific pages into separate files. PDFWhisk's split tool handles this in the browser. You specify which pages to extract (by page number or by range) and download the resulting files. A practical example: you receive a 20-page PDF contract but only need to countersign and return pages 4 and 5, split those out, sign them, and send just those two pages rather than the whole document.
Removing pages from a PDF on iPhone
If you have a PDF with pages you want to delete, a bank statement you want to trim before sending to a third party, a report with a confidential appendix, a printout with a blank page at the end, PDFWhisk's delete pages tool handles this on mobile. Select the pages to remove, and download the cleaned-up file. Nothing leaves your phone.
Converting photos to PDF on iPhone
If you have photographed pages of a document, paper forms, handwritten notes, receipts, converting them to a PDF produces a single clean file for submission or archiving. PDFWhisk's JPG to PDF converter accepts multiple photos at once and combines them into a multi-page PDF, with each photo as one page. Open it in Safari, select your photos from the image picker, and download.
Alternatively, for a single photo, the iOS Print to PDF trick works without any tool: open the photo in Photos, tap Share, tap Print, then pinch-zoom outward on the print preview thumbnail. This converts the preview to a PDF that you can share via the standard iOS share sheet.
Rotating pages on iPhone
Scanned documents sometimes come in the wrong orientation, sideways or upside down. The Files PDF viewer does not have a rotation save function (you can rotate the view temporarily, but it does not save). PDFWhisk's rotate tool saves the rotation permanently: choose the pages to rotate, the direction, and download the corrected file.
Watermarking a PDF on iPhone
If you need to add a "CONFIDENTIAL" label or a name watermark before sharing a document, PDFWhisk's watermark tool does this in the browser. Type the watermark text, set the opacity and angle, and download. A light diagonal watermark across every page is a standard practice for draft documents and confidential reports shared for review.
Quick tips for PDF workflows on iPhone
Save frequently used tools to your home screen. In Safari, navigate to a PDFWhisk tool page, tap Share, and choose Add to Home Screen. This creates a shortcut that opens the tool directly, the experience is close to a native app.
Use iCloud Drive to move PDFs between iPhone and Mac. Process a PDF on your phone (compress, sign, trim), save it to iCloud Drive, and it appears on your Mac's Finder immediately. This is faster than emailing files to yourself.
Check file sizes before uploading. In the Files app, long-press a PDF and tap Info to see its size. If it is over your portal's limit, compress it first.
The Files app supports folders. Create a folder (tap the three-dot menu in Files, then New Folder) to organise PDFs by project, client, or type. This is much easier to navigate than a single flat directory of downloaded files.
iPhone is a fully capable PDF tool when you know what is built in and where browser-based tools fill the gaps. For most everyday tasks, compressing, merging, signing, converting, you do not need to install anything at all.