How to merge multiple PDF files into one
You often need several PDFs in a single file: all the lectures of a course, a month of invoices, or scanned pages for an official application. One file is easier for the person receiving it, tidier to archive and harder to lose a part of.
Filezain’s Merge PDF tool works entirely in your browser: the files are read and combined on your device, never uploaded, and you don’t need an account.
When you need it
- Handing in an assignment or paper made of several parts as one file.
- Sending the documents of an application (ID, certificate, letter) by email.
- Archiving monthly invoices or statements in one yearly file.
- Adding a cover page or a signature page to a finished report.
Steps
- Open the Merge PDF tool.
- Add the files in the order you want them in the final document: the first file you add becomes the first pages.
- Check the file list and remove anything added by mistake with ×.
- Press the convert button and wait for the merge to finish.
- Download the result (filezain-merged.pdf).
Tips
- The order of the final file is the order in which you added the files. For a different order, clear the list and add them one by one in the right order.
- If you only need certain pages of a long file, extract them first with Split PDF, then merge.
- Merging doesn’t re-compress pages, so every page keeps its original quality.
- If the result is too big to send, run it through Compress PDF afterwards.
Common problems and fixes
- An error appears when adding a certain file.
- It’s most likely password-protected. Remove the password first with Unlock PDF, then merge.
- The pages are in the wrong order.
- Press Clear and add the files again, one by one, in the order you want.
- Merging is slow on my phone.
- Very large files need more memory. Merge them in two batches, then merge the two results.
- Some pages are upside down.
- Pages keep the orientation of the original file; fix them afterwards with Rotate PDF.
Frequently asked questions
Are my files uploaded to the internet?
No. Merging happens inside your browser on your device.
Does page quality drop?
No. Pages are copied as they are, with no re-compression.
Does it work on an iPhone?
Yes, in Safari or any modern browser, with no app to install.
Is there a limit on the number of files?
There’s no fixed limit; the practical limit is your device’s memory. Each file can be up to 250 MB.