When you need to watermark a batch of PDFs with the same text — CONFIDENTIAL, DRAFT, or your company name — the fastest free method is to merge them, watermark in one pass, then split if needed. Here is how.
Go to pdfeditor.onl/organize-pdf and upload all the PDFs you want to watermark. Click Merge & Download to combine them into a single file. This lets you apply the watermark in one operation.
Go to pdfeditor.onl/watermark-pdf. Upload the merged PDF. Set your watermark text, font size, opacity, rotation, and position. Click Apply to All Pages.
Tip: For batch watermarking, a diagonal center watermark at 30–40% opacity is most readable without obscuring content. Use a font size of 60–80pt for letter/A4 pages.
If you need the files separate again, go to pdfeditor.onl/organize-pdf, upload the watermarked merged PDF, switch to Split mode, and define page ranges for each original document.
For a small number of files (2–5), it may be faster to watermark each PDF individually through pdfeditor.onl/watermark-pdf. The process takes about 30 seconds per file.
No enforced limit. Your browser's available RAM is the only constraint. Most modern computers handle 20–30 merged PDFs smoothly.
The merge-then-watermark method applies the same watermark to all pages. For different watermarks per file, process each file individually.