Add Watermark to PDF
Add a text watermark to a PDF on Toolomix via Stirling-PDF—opacity, font size, rotation, color, and optional PDF-image flatten.
Protect Your PDF with a Watermark
Add a customizable text watermark to your PDF on Toolomix servers via Stirling-PDF — no desktop software to install.
Drag and drop your PDF file here or click to browse
Supported: .pdf files onlyTips
Balance opacity
Lower opacity keeps page content readable while still marking the document.
Use rotation for drafts
A diagonal angle is a common choice for DRAFT or CONFIDENTIAL labels.
Review after download
Open a few pages of the result to confirm size, color, and spacing look right.
Text watermark controls
Set watermark text, font size, opacity, rotation, color, and width/height spacers.
Server-side via Stirling-PDF
The PDF is uploaded and watermarked on Toolomix through Stirling—not with client-side pdf-lib.
Optional PDF-image flatten
Enable convertPDFToImage to flatten the watermarked output into an image-based PDF.
What this tool does
Add Watermark to PDF overlays a customizable text watermark on a PDF so you can mark drafts, confidential copies, or ownership before sharing.
Appearance is controlled with font size, opacity, rotation, color, and spacing; an optional flatten step can turn the result into a PDF-image.
How to use
Upload one PDF
Select or drag a single .pdf file (not encrypted).
Configure the text watermark
Enter text and adjust font size, opacity, rotation, color, and spacers; optionally enable PDF-image flatten.
Add watermark and download
Submit the job and download the watermarked PDF when processing finishes.
Supported inputs and output
Input: one .pdf, watermark text, opacity, fontSize, rotation, color, spacers, convertPDFToImage flag. watermarkType is sent as text. Posted to /api/converter/pdf-add-watermark (~100 MB).
Output: one watermarked PDF. Image watermarks are not exposed in this UI.
Processing and privacy
The PDF is uploaded over HTTPS and watermarked on Toolomix servers through Stirling-PDF—not with client-side pdf-lib.
Toolomix does not publish a verified universal retention clock for every conversion. See the Privacy Policy for how uploads and logs are handled.
Limitations
Known limits
- Text watermark via UI only (watermarkType hardcoded to text)
- No password / encrypted-PDF unlock
- Single PDF per request
- About ~100 MB upload ceiling
- Not processed with browser pdf-lib
- Flatten option increases file size and rasterizes pages
Troubleshooting
If watermarking fails, confirm the file opens locally, remove any password protection, keep the upload under ~100 MB, and retry.
If the mark is hard to see or too strong, adjust opacity, font size, rotation, or spacers and run again; review the downloaded PDF before sharing.
Frequently Asked Questions
Is the watermark text-only in this UI?
Yes. The page hardcodes watermarkType to text. You configure a text watermark; there is no image-watermark picker in the UI.
Where is watermarking processed?
Your PDF is posted to /api/converter/pdf-add-watermark and processed on Toolomix servers via Stirling-PDF’s watermark API—not in the browser with pdf-lib.
Which options can I set?
Watermark text, opacity, font size, rotation, text color, width/height spacers, and an optional convert-to-PDF-image flatten.
Can I watermark a password-protected PDF?
No. There is no password unlock field. Remove encryption before uploading.
What is the file size limit?
Approximate upload limit is about 100 MB. Larger files may be rejected by middleware.
What does flatten to PDF-image do?
When enabled, convertPDFToImage is sent so the watermarked PDF can be flattened into an image-based PDF, which can make later text edits harder.
Can I watermark several PDFs in one request?
No. Upload and process one PDF per request.
Try Other Free Tools
Use Add Watermark to PDF
Set text, opacity, rotation, and color, then watermark the PDF on Toolomix servers.
