These tools can do multiple tasks like merging, splitting, organising PDFs and much more.

• Merge — combine any number of PDFs into one, in an order you control
• Organise pages — keep only the pages you want, delete pages, put them in a new order, or rotate them
• Split — break a document into separate files, either one file per page or by ranges you specify
• Images to PDF — turn JPG and PNG files into a single document, sized to A4 or to the images themselves
• Page numbers — stamp numbers in any corner, starting from any number, with an optional "page 3 of 20" format
• Watermark — add draft, confidential, or your own wording, at an angle and opacity you choose

How to write a page range

Anywhere a page range is asked for, write it the way you would on paper: 1-3 for the first three pages, 2,5,9 for particular pages, 7- for page seven to the end, or a mixture such as 1-3,7,12-. Pages are numbered as you see them in a reader, starting at one.

How large a file can it handle

The limit is your device's memory rather than any rule we impose. A PDF has to be held in memory in full while it is being changed, and the output is built alongside it, so a rough guide is that a file needs about three times its own size in free memory. On a normal desktop or laptop, files up to about 100 MB are comfortable and 200 MB usually works. On a phone, expect trouble beyond about 30 MB. The tool warns you before it starts if what you have selected looks too heavy, and it tells you plainly if the browser runs out of memory rather than failing silently.

What these tools cannot do

They cannot open a PDF locked with a password — remove the password in the program that created it first. They do not reduce file size, because worthwhile compression means re-encoding the images inside the document and that is genuinely server work. They do not read scanned text, and they do not edit words already in a document; a PDF is a fixed layout and changing existing text properly needs the original file.