No watermark on the free plan. No watermark on Premium. There's never been one to unlock — merging happens in your browser, so there's no server-side branding step to add one.
Why "no watermark" needs saying out loud
Plenty of "free" tools
Merge for free — then stamp a logo across every page, or hide "no watermark" behind a paid plan you discover after uploading.
PDFLite
Output is exactly the bytes of your original pages, recombined. Nothing added, ever.
How it actually works
No upload progress bar, because there's no upload. The merge runs locally with a JavaScript library called pdf-lib, using your browser's own processing power. A watermark would have to be added by code running openly on your machine — which is exactly why there's nothing to "unlock" as a paid feature.
What the free plan actually limits
To be upfront about it, unlike tools that bury this in fine print:
3/day
Merge or split actions, resets midnight
15 pages
Per job, counted across all files
Go over either and you'll be offered Premium — $5/month, unlimited merges/splits, no page cap. No watermark at any tier.
Who this is for
Merging anything you wouldn't want sitting on a stranger's server even briefly — a client contract, a patient record, a set of financial statements. No upload means no server log, no "we delete files after 1 hour" policy to trust, and no watermarking step that would require touching your file server-side in the first place.