A PDF that travels without a label can be mistaken for the final version, an internal memo or a free sample. Kwebby's Watermark PDF tool lets you add a watermark to a PDF in seconds: type words such as DRAFT, CONFIDENTIAL or your company name, choose a color, opacity, angle and size, and the tool stamps every page. It runs in your browser, so the document stays on your device. This guide explains each control, the settings that read well and the limits to know before you rely on a watermark. More free PDF tools are a click away.
Key Takeaways
- Kwebby's Watermark PDF tool adds one line of text to every page of a PDF, in the color, opacity, angle and size you choose.
- The defaults are CONFIDENTIAL, red, 30 percent opacity, 45 degrees and size 60. Opacity runs from 5 to 100 percent, angle from 0 to 90 degrees and size from 20 to 120.
- The text is centred on each page along the angle you choose. Very long text at a large size can still run past the page edge, so shorten it or lower the size.
- The tool supports text only, on all pages. Image watermarks, page selection and font choice are not available.
- A visible watermark discourages casual reuse but is not tamper-proof. Always keep your original file.
- Processing happens in your browser, and the result downloads as a new file ending in -watermarked.pdf.
What Is the Kwebby Watermark PDF Tool?
Kwebby's Watermark PDF tool is a free, browser-based utility that adds a line of text, such as DRAFT or CONFIDENTIAL, to every page of a PDF. You choose the text, color, opacity, angle and size, click Apply Watermark and download the stamped copy. The tool works on your device and leaves your original file unchanged.
The words become part of each page's content. They print with the page and show in every PDF viewer, and they sit over the existing text and images, so a light opacity keeps the page readable underneath.
Key Features and How It Works
Five Controls
| Control | Range | Default |
|---|---|---|
| Watermark Text | Any text, cannot be empty | CONFIDENTIAL |
| Opacity | 5 to 100 percent, in steps of 5 | 30 percent |
| Angle | 0 to 90 degrees, in steps of 5 | 45 degrees |
| Font Size | 20 to 120, in steps of 5 | 60 |
| Color | Any color from the color picker | Red |
The Same Text on Every Page
The tool loops through each page and draws your text once per page. There is no page range, so a 40 page report gets 40 watermarks. To stamp only part of a document, cut it first with Split PDF.
Centred on Every Page
The tool measures the text and places its middle on the middle of each page, then tilts it to the angle you set. At 45 degrees it runs diagonally from lower left to upper right, and at 0 degrees it runs straight across the centre.
Local Processing and Automatic Download
The tool opens your PDF with pdf-lib, an open-source JavaScript library, inside your browser. It does not upload the file. When it finishes, your browser downloads a copy named like your original with -watermarked added before .pdf.
Why Watermark a PDF
A watermark tells every reader what a document is before they read a word. It is the quickest way to add a watermark to a PDF when you need a status label, an ownership mark or a deterrent for casual copying.
- Status: DRAFT warns people not to treat a proposal or contract as final.
- Handling: CONFIDENTIAL signals that a file should not be forwarded.
- Ownership: a company name or web address on a shared document keeps the source visible when it moves between inboxes.
- Previews: SAMPLE on a paid report or template makes the free copy less useful as a substitute.
Be realistic about strength, though. A visible watermark is a label, not a lock. In an Adobe Community thread on permanent watermarks, an expert reply says removal is not so easy but not impossible, and that no method is 100 percent secure. Treat the watermark as a deterrent and a signal.
How to Use the Watermark PDF Tool
You need one PDF file. The steps take under a minute.
- Click the upload area or drag a PDF onto it. The file name appears in the box.
- Type your text in the Watermark Text box. The default is CONFIDENTIAL.
- Move the Opacity, Angle and Font Size sliders and pick a Color.
- Click Apply Watermark. The button shows Applying while the tool works.
- Open the downloaded -watermarked.pdf and check the first and last pages.
Best Practices for Watermarking PDFs
Keep the Text Short
Length still matters, because the text is drawn on one line. CONFIDENTIAL is about 440 points wide at size 60 (roughly 6.1 inches), which fits an A4 or Letter page at 45 degrees. At 0 degrees and size 120 the same word is about 880 points wide, wider than the page, so both ends are cut off. Lower the size or use a diagonal angle for long text. If the preview in your viewer shows a clipped word, run the tool again with a smaller size or a shorter phrase.
Pick an Opacity You Can Read Through
Opacity between 20 and 40 percent usually keeps body text readable while the mark stays visible. Above 60 percent the watermark starts to hide the content underneath, which defeats the point of sharing the document.
Match the Angle to the Job
A 45 degree diagonal is the familiar stamp look. Use 0 degrees for a plain horizontal label and 90 degrees for a vertical one. Angles run from 0 to 90 only.
Use Standard Latin Letters
The tool draws text with a standard Latin font. Accented letters and symbols such as the copyright sign and the euro sign work. Characters outside that set, such as Chinese or Cyrillic letters, trigger an error message and no file is produced.
Keep Your Original
The tool adds watermarks and does not remove them. Save the unmarked file first so you can issue a clean version later.
Order Your Workflow
Put watermarking near the end. Merge PDF first if you are combining files, and Rotate PDF if any page is sideways, because a watermark added to a sideways page reads sideways too. Run Compress PDF afterwards if the file needs to be smaller.
Know What a Watermark Cannot Do
A watermark does not stop anyone from copying text, printing or editing. It also will not survive a determined attempt to remove it. If you need it harder to remove, the Adobe Community expert suggests converting pages to images. With Kwebby you can do that by running PDF to JPG on the stamped file and rebuilding the pages with JPG to PDF. Expect a larger file, and the text will no longer be selectable or searchable.
Common Use Cases
- Contracts and proposals: mark unsigned versions DRAFT.
- Internal reports: add CONFIDENTIAL before sharing across teams.
- Samples and previews: stamp SAMPLE on pages you show before a sale.
- Brand marks: put your company name on documents that go to clients.
- Version tracking: use text like v2 so reviewers know which copy they hold.
- Scanned copies: label a scan COPY so it is not mistaken for the original.
Related Kwebby Tools
- Merge PDF joins several PDFs before you stamp them.
- Split PDF pulls out the pages you want to mark.
- Rotate PDF fixes sideways pages so the watermark reads correctly.
- Compress PDF rewrites the file structure after stamping. Savings vary with the content.
- JPG to PDF builds a PDF from images, for example after flattening pages.
Frequently Asked Questions (FAQs)
How do I put a watermark on a PDF?
Open Kwebby's Watermark PDF tool, add your file and type the watermark text. Set the opacity, angle, size and color, click Apply Watermark and open the downloaded -watermarked.pdf. Every page carries the text.
Can I make a PDF watermark permanent?
The tool draws the text into each page's content, so it shows in every viewer and prints with the page. No setting hides it. A determined person with a PDF editor can still remove it, so keep your original and treat the mark as a deterrent.
Can I watermark only some pages or use an image?
No. The tool applies one line of text to every page and has no image or page range option. To stamp part of a file, use Split PDF to extract those pages first.
Why is my watermark cut off at the edge?
The text is centred on the page and drawn on one line, so long text at a large size can be wider than the page. At size 120 and 0 degrees, CONFIDENTIAL is wider than an A4 page. Lower the size, use a diagonal angle or shorten the text.
What opacity and angle work best?
An opacity of 20 to 40 percent and an angle of 45 degrees suit most documents. Raise opacity for short words on light pages, and lower it when the page has dense text.
Is the Kwebby Watermark PDF tool free, and is my file uploaded?
The tool is free to use, with no account or payment. It processes your PDF in your browser and does not upload it to a server.
Final Thoughts
A good watermark takes a short phrase, a readable opacity and a quick look at the result. Kwebby's Watermark PDF tool keeps that workflow simple: pick the words, set the look, stamp every page and download. Remember the limits, keep your original and use the marks as labels rather than locks. When the file is ready, merge, compress or share it with the rest of the PDF toolset.