🖼️ Image Watermark Tool
By Shihab Mia · Updated 2026-07-31
PNG, JPEG, WebP and GIF are supported. Your image never leaves your browser.
Upload an image to begin. Everything runs locally on your device.
This image watermark tool lets you stamp a text watermark onto any photo right in your browser. Upload an image, type your watermark text, then fine-tune the position, opacity, font size and color until it looks right. The preview updates instantly and you can download the finished image with one click. Nothing is uploaded to a server, so your photos stay private on your own device.
What is the Image Watermark Tool?
A watermark is a piece of text or a logo placed over an image to mark ownership, discourage unauthorized reuse, or simply brand your work. The most common kind is a semi-transparent text watermark, for example a name, website or copyright line, sitting in a corner of the photo. Because it is partly see-through, it identifies the source without hiding the picture underneath.
This tool builds the watermark entirely with the HTML canvas. When you load an image it is drawn onto a canvas at its full native resolution, then your text is painted on top using the font size, color and opacity you choose. Opacity is the key setting: a value around 40% to 60% is usually visible enough to claim the image yet light enough not to spoil it. A subtle drop shadow is added by default so light text stays readable on light backgrounds and dark text on dark ones.
Watermarking serves several different goals, and the right settings change depending on which one you care about. A photographer sharing samples online usually wants a small, low-opacity corner mark that says "here is who made this" without distracting from the shot. A business posting product photos wants a mark that survives screenshots and reposts, so it often sits larger and closer to the center. A designer sending drafts to a client wants something loud and hard to miss, like a diagonal or centered "PROOF" or "SAMPLE" label, because the goal there is to prevent the unfinished version from being used, not to look elegant.
Compared with desktop editors like Photoshop or GIMP, a browser-based watermark tool trades advanced features such as batch processing, saved presets and image-logo overlays for speed and zero setup. You do not install anything, create an account, or wait for an upload. For a single photo, or a handful done one at a time, that trade is almost always worth it. If you need to watermark hundreds of images identically, a batch desktop tool or a scripted solution is the better fit, but for everyday sharing and posting this in-browser approach is faster and keeps the original file private.
Everything happens locally in your browser using FileReader and the canvas API, with no network requests. When you download, the canvas is exported with toBlob as a PNG, which preserves the watermark crisply and supports transparency. Because the watermark is rendered at full resolution, it scales with the image rather than looking pixelated, and the original file on your computer is never modified or sent anywhere.
When to use it
- Adding a copyright line or your name to photos before posting them on social media or a portfolio.
- Branding product images, screenshots or infographics with a website URL so reshares still point back to you.
- Marking draft or sample images with text like "PROOF" or "SAMPLE" before a client approves the final version.
- Protecting images you sell or license by stamping ownership text that discourages casual copying.
- Labeling preview photos for an online store or marketplace listing so shoppers see full quality but cannot lift a clean copy.
- Adding a quick date, event name or location stamp to photos before archiving or sharing them with a group.
How to use the Image Watermark Tool
- Choose an image file from your device. It loads instantly and stays in your browser.
- Type the watermark text you want, such as your name, a copyright symbol, or a website.
- Pick a position (a corner or the center) and adjust the color, font size and opacity.
- Toggle the shadow on or off for legibility, then check the live preview.
- Click Download watermarked image to save the result as a PNG.
Formula & method
Worked examples
A 1600 px wide photo, watermark font size set to 6%.
- font size = (6 ÷ 100) × 1600 = 96 px
- Opacity slider at 50% gives an alpha of 0.5
- White text #ffffff becomes fill rgba(255, 255, 255, 0.5)
- With position bottom-right, the text is anchored to the lower-right corner inside the margin
Result: A semi-transparent 96 px white watermark sits in the bottom-right corner.
An 800 px wide image, font size 10%, opacity 80%, center position.
- font size = (10 ÷ 100) × 800 = 80 px
- Opacity 80% gives an alpha of 0.8
- Center position anchors the text at (400, the vertical middle) with centered alignment
Result: A bold 80 px watermark sits centered across the middle of the image at 80% opacity.
A 3000 px wide product photo for an online store listing, font size 5%, opacity 35%, bottom-left position.
- font size = (5 ÷ 100) × 3000 = 150 px
- Opacity 35% gives an alpha of 0.35
- Bottom-left anchor places the text inside the lower-left margin
Result: A light 150 px watermark sits unobtrusively in the bottom-left corner, keeping the product clearly visible while still marking the source.
Suggested watermark settings by goal
| Goal | Position | Opacity | Font size |
|---|---|---|---|
| Subtle branding | Bottom right | 30% to 45% | 4% to 6% |
| Clear ownership | Bottom right or left | 50% to 65% | 6% to 8% |
| Strong anti-theft | Center | 40% to 60% | 10% to 16% |
| Draft or proof label | Center | 50% to 70% | 12% to 20% |
Choosing a format for the watermarked download
| Format | Best for | Watermark quality | File size |
|---|---|---|---|
| PNG (this tool's output) | Sharing online, printing, further editing | Crisp edges, true transparency support | Larger, lossless |
| JPEG | Email attachments, web thumbnails | Slight softening from compression around the text | Smaller, lossy |
| WebP | Modern websites, fast page loads | Good quality at a small size | Smallest, needs converting from the PNG |
Common mistakes to avoid
- Setting opacity too high. A watermark at 90% or 100% opacity covers the image and looks unprofessional. Most watermarks sit between 30% and 60% so they are visible without overwhelming the photo.
- Using a color that blends into the background. White text vanishes on a bright sky and black text disappears on a dark scene. Keep the shadow on, or switch the text color to contrast with the area where the watermark sits.
- Placing the watermark where it is easy to crop out. A tiny corner watermark can be cropped away in seconds. For stronger protection use the center position or a larger size so removing it would damage the image.
- Expecting a watermark to be uncopyable. A visible text watermark deters casual reuse but a determined editor can sometimes remove it. Treat it as a deterrent and a credit, not a guarantee against theft.
- Watermarking a low-resolution image and expecting a crisp result. The watermark is only as sharp as the source photo. If you start from a small or heavily compressed image, both the picture and the text will look soft no matter what settings you choose.
- Not keeping an unwatermarked master copy. Once you download the watermarked PNG, keep your original file too. If you ever need to print, sell, or license the image cleanly, you will want the un-marked version on hand.
Glossary
- Watermark
- Text or a logo overlaid on an image to mark ownership or source, usually semi-transparent so the picture stays visible.
- Opacity
- How solid the watermark text appears, from 0% (invisible) to 100% (fully opaque). Lower values let the image show through.
- Canvas
- The HTML drawing surface this tool uses to combine your image and the watermark text entirely in the browser.
- PNG
- A lossless image format that preserves sharp text and transparency, used here for the downloaded watermarked file.
- Anchor
- The reference point the text is aligned to, such as the bottom-right corner or the center of the image.
- Alpha channel
- The part of a pixel that stores transparency. A watermark's opacity setting controls the alpha value of the text so the image underneath can show through.
- Drop shadow
- A soft dark or light outline behind the watermark text that keeps it readable against busy or similarly colored backgrounds.
- Tiled watermark
- A watermark pattern repeated across the whole image rather than placed once, used by some tools for stronger anti-theft protection.
Frequently asked questions
How do I add a watermark to a photo?
Upload your image, type the text you want as a watermark, then choose a position, color, font size and opacity. The preview updates as you go, and the Download button saves the watermarked image to your device.
Is this image watermark tool free?
Yes. The tool is completely free with no sign-up, no limits and no watermark of our own added to your image. You only see the text you type.
Are my images uploaded to a server?
No. Everything runs in your browser using the canvas and FileReader APIs. Your photo is never sent over the network, so it stays private on your own device.
What image formats can I watermark?
You can load PNG, JPEG, WebP and GIF images. The watermarked result is exported as a PNG, which keeps the text sharp and supports transparency.
What opacity should I use for a watermark?
For most photos an opacity between 40% and 60% works well: visible enough to claim the image but light enough not to spoil it. Lower it toward 30% for subtle branding or raise it for a stronger mark.
Can I add an image or logo as the watermark instead of text?
This tool overlays text watermarks, including a copyright symbol or website. For a logo watermark you would composite a second image, which this tool does not currently do, so it focuses on clean, adjustable text.
Does adding a watermark reduce my photo's quality?
No. The image is drawn onto the canvas at its full native resolution and exported as a lossless PNG, so the picture itself is not recompressed or resized. Only the watermark text is added on top.
Can I watermark several photos at once?
This tool processes one image at a time so you can fine-tune the position and opacity for each photo individually. For a large batch that all needs the identical mark, a dedicated batch-watermarking desktop app will be faster.
Can I rotate or tile the watermark text?
The current version places a single horizontal watermark at a chosen anchor point (a corner or the center) rather than rotating it or repeating it in a tiled pattern across the image. For most branding and proofing needs a single well-placed mark is enough.