You have three PDFs on your phone — a scanned form, a photographed receipt, a letter someone emailed — and the portal wants one file. The app store offers you a merge app with a subscription and an account. You do not need it. Your phone’s browser can do the whole job on the device, and the files never go anywhere.
Before you start
Have the PDFs somewhere the browser’s file picker can reach:
- iPhone and iPad: the Files app (iCloud Drive, On My iPhone, or any connected storage). Email attachments can be saved to Files with the share button.
- Android: Downloads, Drive, or any folder the Files app shows. Attachments save to Downloads.
Photos of documents are not PDFs yet. Turn them into one with JPG to PDF first, or photograph pages directly with Scan to PDF, which straightens and sharpens them on the device.
Step by step
- Open Merge PDF in Safari or Chrome.
- Tap the file area. The system picker appears; select every PDF you want to combine. On iOS, tap Select in the picker to choose several; on Android, long-press the first and tap the others.
- The pages appear as thumbnails, each with a coloured strip for the file it came from. On a phone, dragging scrolls the grid instead of moving a page, so the pages stay in the order the files arrive in, which is not always the order you tapped them. Check it, and use each page’s turn and remove buttons to fix what you can.
- Tap the run button. The merge happens in the tab; a receipt shows how many document bytes were sent, which is zero.
- Save. Safari offers a download that lands in Files; Chrome on Android saves to Downloads. From there you can share it to the portal, email or a message.
If a page came out the wrong way round, turn it before you merge with its turn button, or save the merged file and choose it again in Rotate PDF. Putting pages in a different order needs a computer, in Merge PDF or Organize PDF pages, because dragging does not move pages on a touch screen.
What to expect
- Speed. A few text documents merge in a second. Scans are bigger and take longer, but merging does not re-render pages, so even large files are quick unless memory runs short.
- Memory. The phone holds every page in the tab’s memory. A hundred full-page colour scans at 600 DPI may exceed what the browser allows. Run the largest file through Compress PDF first, or merge in batches.
- Background tabs. Mobile browsers pause background tabs. Keep the page in front until the download prompt appears.
- Connection. Stay online until the merged file is ready: parts of the engine download when you choose files and when you press Merge. Your PDFs are never part of those downloads.
Why this is safe to do with a real document
An app or an online service that merges your files has your files. The browser approach never sends them anywhere: the PDFs are read into the tab’s memory, combined there, and written back to the phone. Open the browser’s developer tools on a laptop some time and watch the Network panel while merging — here is how. On the phone, the receipt under the result is the same information in one line.