Mac users have a quiet pleasure: dragging one PDF onto another in Preview's sidebar combines them. Most people don't know. Once you do, you wonder why other OSes don't have it.
For small jobs, Preview is enough. For anything more, the browser wins.
Preview's drag-and-drop merge
Open the first PDF in Preview. Show the sidebar (View → Thumbnails). Drag the second PDF file from Finder into the sidebar at the position you want. Repeat for any additional PDFs. File → Export as PDF (or just Save) to write out the combined document.
Works for 2–5 files quickly. Gets fiddly beyond that.
When Flint wins
Flint's merger shows all source files in a strip, drag to reorder, batch-merge in one click. Better for 5+ files or when you need to reorder mid-merge. Result downloads as one PDF, ready to share.
Also useful when source PDFs are in different folders or coming from Drive — drop them into Flint without copying to Finder first.
Cleaning up after
Merged PDF often needs tidying. Use reorder PDF pages to fix order, delete pages to drop ones you don't need, rotate if any came in sideways. All in the same Flint session.
FAQ
Will Preview merge keep bookmarks?
Preview preserves bookmarks from individual source PDFs when dragging them in. Some metadata (forms, embedded JavaScript) may not survive. Flint preserves more of the original structure for complex source files.
Can I merge from Finder directly?
Yes — select multiple PDFs in Finder, right-click → Quick Actions → Create PDF. Combines them in alphabetical order. Quick but no reorder control. Open in Preview or Flint to reorder afterward.
Is there a size limit on merges?
Preview handles dozens of files comfortably. Flint does the same. Multi-gigabyte merges work but take longer — both tools chug through them given enough time.
For quick merges, Preview. For batch jobs, Flint. Pick by file count.