No more font or formatting problems after edits
Open one PDF, add the pages of another, and put them in the order you need.
An invoice added after a contract.
Open the PDF and press Strip on the left: the pages are shown as a column of thumbnails.

Press the folder button above the thumbnails and choose the file — or drop it on the strip. Its pages go after the pages you ticked, or at the end.

Drag a thumbnail to move its page. Then download the merged PDF.
The pages of the second file are copied into the first as they are: their text, fonts, pictures and links come along.

Nothing is converted or re-drawn: the added pages keep their text, fonts and pictures.
After the pages you tick in the strip, or at the end if none is ticked.
The merged document is edited like any other: text, signatures, page numbers.
Adding a file is one entry in the list of edits.
Add files one after another.
Move pages in the strip.
Text stays text, fonts stay fonts.
Number the pages, sign, change text.
Tick pages to download only those.
In the browser, on a computer or a phone.
The browser editor keeps documents of up to 50 pages, all files together.
A PDF that needs a password to open cannot be added here.
Number the merged pages with Page numbers after merging.
Open the first, press Strip, then the add-a-PDF button above the thumbnails, and choose the second. Download the result.
Yes: tick the page it should follow, then add the file.
Yes: drag the thumbnails in the strip.