Pick two or more PDFs, put them in the order you want, and combine them into a single file. Nothing is uploaded anywhere; the files never leave this browser tab.
Tap to choose files
or drag them in — pick several at once, or add more later
Scales every page to match the width of the first PDF's first page — useful if your files are different sizes and pages currently come out narrower or wider than each other.
Trade-off: normalized pages are rendered as images, not live text. Text on those pages won't be selectable, searchable, or copyable afterward. Leave this off if your files are already a consistent size, or if you need to keep selectable text.
Renders at a higher resolution for crisper text — larger file size. Only applies when "Match page sizes" is on.
How it works. This page loads MuPDF compiled to WebAssembly and combines the PDFs in your browser's memory — the same engine desktop PDF tools use, just running locally instead of on a server. First load pulls down about 10 MB of engine files; after that it works from cache.