What this tool does
Choose an image, edit the watermark text, adjust placement, opacity, and size, then export a PNG. Selected image contents are processed locally in your browser.
Privacy behavior
Selected file contents are processed locally in your browser for supported workflows. This privacy build does not intentionally load ads, analytics, remote fonts, or third-party runtime scripts.
Supported workflow
Use the controls on this page, review the output in your browser, then copy or download the result.
When should you watermark an image?
Watermarks help mark ownership, prepare drafts, label previews, and share images while keeping brand or source context visible.
Keep watermarks readable without covering important image details. For privacy-sensitive photos, remove metadata before publishing.
What this tool actually does — and its real limits
This is a text-only watermark stamper: there is no option to upload a logo or image as the watermark itself, only a text string drawn with the browser's Canvas 2D text APIs (fillText/strokeText). The visible style is fixed — white fill with a semi-transparent black outline — and is not user-configurable beyond opacity and size; there is no color picker.
Regardless of the source image's format, the output is always a PNG exported with canvas.toBlob(..., "image/png"). Uploading a JPG and watermarking it still produces a PNG download, which is typically larger than a re-exported JPEG would be for a photo, since PNG is lossless. This tool also processes one image at a time; unlike most other tools on this site, there is no batch queue or ZIP export for multiple files.
The nine position presets place the text at a margin computed from the watermark's own font size (roughly 0.9 times the font size, with a 12px minimum), and font size itself is computed as a percentage of the image's own width (the Size slider), not a fixed pixel value:
| Image width | Size 2% (min) | Size 6% (default) | Size 18% (max) |
|---|
| 800 px | 16 px font | 48 px font | 144 px font |
| 2000 px | 40 px font | 120 px font | 360 px font |
| 4000 px | 80 px font | 240 px font | 720 px font |
Opacity ranges from 10% to 100% (default 70%) and applies to the whole watermark, text fill and outline together, via globalAlpha.
Position grid reference
| Left | Center | Right |
|---|
| Top | Top left | Top center | Top right |
|---|
| Middle | Middle left | Center | Middle right |
|---|
| Bottom | Bottom left | Bottom center | Bottom right (default) |
|---|
Each preset anchors the text to that edge or center of the image, offset inward by the computed margin; there is no free-drag positioning or custom offset field.
Failure modes and limits
- One image at a time. There is no batch mode; watermarking several photos means repeating the process for each one.
- Fixed output format. The download is always PNG; there is no option to export a watermarked JPG or WebP, even from a JPG source.
- No image-based watermark. Logo or stamp images cannot be used as the watermark; only typed text is supported.
- Very large source images. Extremely large photos can approach a browser's maximum canvas dimensions, a limit that varies by browser and device; if the preview fails to render, try a smaller source image.
- Fixed text styling. Color (white fill, black outline), font family, and weight are not configurable; only text content, position, opacity, and size can be adjusted.
Frequently Asked Questions
Is this Watermark Tool free?
Yes. You can add and download a text watermark without signup.
Are my images sent to ConvertUnlimited servers?
No server-side upload endpoint is used for this watermarking flow. The image is processed locally in your browser.
Can I change watermark position?
Yes. Choose corner, center, or edge positions before exporting.
Can I adjust opacity and size?
Yes. Use the sliders to tune the watermark preview.
What format is exported?
The tool exports a PNG image from the browser canvas.
Can I watermark multiple images at once?
No. This tool processes one image at a time; there is no batch queue or ZIP export here, unlike most other tools on this site.
Can I use a logo image instead of text?
No. Only typed text watermarks are supported; there is no option to upload a logo or stamp image as the watermark.
Why is my watermarked download always a PNG, even from a JPG source?
The export path always writes PNG regardless of the source format. If a smaller file matters more than lossless output, re-compress the downloaded PNG with a tool such as Image Compressor.
Privacy
Privacy build: This build removes ads, analytics, remote fonts, runtime CDN scripts, and file-operation telemetry. Selected files are processed in the browser using local JavaScript and browser APIs.
ConvertUnlimited does not provide a server-side upload endpoint for this watermarking flow. Selected image contents are processed locally in your browser.
Terms of Use
ConvertUnlimited is provided as is. You are responsible for the images and watermark text you create.
Trust and privacy
Files are processed locally where supported. Review the Trust Center for the processing model and the Privacy Policy for public-site privacy boundaries.