Tool
PDF Studio — merge, split and reorder PDFs offline
$5 one-time
Anyone assembling a submission out of several PDFs — grant applications, tender documents, visa paperwork, insurance claims.
The pages arrive as separate files, some scanned sideways, and the portal accepts one PDF under a page limit.
Free merge sites that upload the documents, or a paid Acrobat subscription for a task that takes five minutes a month.
The same operations with nothing uploaded, no account, and no subscription — and it keeps working years later because there is no service to shut down.
Weak differentiation. Free tools do this adequately, and the privacy argument is thinner for a document you were going to submit anyway.