How to merge
- Add at least two PDF files with the picker or by dropping them on the page.
- Check the first-page preview, the page count, and the file size.
- Drag a card, or use Move up and Move down, until the list matches the document you want.
- Choose Merge PDF, then Download PDF. The file name is pdfzaro-merged.pdf.
What happens to quality
The merge copies PDF pages. It does not photograph them or rebuild them from a preview image. Text that was searchable stays searchable. Drawings stay as vectors. Pictures embedded in a page stay pictures. The new file is rewritten, so its size can differ a little from the sum of the inputs, without a JPEG quality step.
Ordering
The top card becomes the start of the document. Nothing is sorted by file name. Add more files at any time; new files are placed at the end until you move them.
Privacy
Reading, previewing, and merging happen in this browser. The PDF bytes are not posted to PDFZaro. The page does load its own scripts and the merge engine from this site. That traffic is the program, not your document.
Browsers
Use a current version of Chrome, Edge, Firefox, or Safari, including current mobile Safari and Chrome. The merge engine is WebAssembly. If the browser cannot start it, the page says so instead of sending the files elsewhere.
Limits
- Password-protected PDFs are refused. The tool does not ask for the password.
- A file that is not a PDF, or a PDF so damaged it cannot be opened, is refused. Damaged files are not quietly repaired into the result.
- Page size, rotation, searchable text, vectors, embedded images, and link addresses on a page are kept.
- Form fields are kept. If two files use the same field name, the later field is renamed with a +1 suffix so the values do not overwrite each other.
- Bookmarks and the document title and author are not copied into the merged file.
- Scanned pages are not turned into text. There is no OCR step.
- A selection stops at 20 PDF files, 80 MB for one file, or 100 MB combined. That ceiling keeps the tab from holding an unbounded document. It is a safety guard, not a measured phone maximum. Smaller files can still fail if the device runs out of memory, and the page shows that error instead of a partial download.
Questions
Are my PDFs uploaded?
No. The merge runs in your browser. The site does not receive the file bytes, the file name, or the text inside the PDF.
Will I still be able to search the text?
Yes, when the original pages already contain real text. A scan that is only an image stays an image.
Can I change the order after I add the files?
Yes. Drag a file, or use Move up and Move down. The visible order is the order in the download.
What about a password-protected PDF?
It is rejected with an explanation. Unlocking files is not part of this tool.
Is there a fixed size limit?
Yes. Up to 20 PDF files, 80 MB for one file, and 100 MB combined. These are safety limits. A smaller selection can still fail on a phone with little free memory.
Does the phone version work?
The same page is used. Reordering has buttons as well as dragging, so it does not depend on a mouse.