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Image Watermark

Overlay text watermarks on images in your browser: full-image tiling, center or corner placement, adjustable size and opacity. Photos never leave your device.

Photos get copied and unattributed images get reused, and a text watermark applied in the browser is the cheap defence: tiled across the whole image, or placed in the centre or a corner, with adjustable size and opacity, and a one-click download afterwards. A handle or account name is the right content, so anyone who reposts the picture can find its source — and the image is never sent to a server.

For protection, tile across the whole image at 15–25% opacity; covering it line by line is expensive to remove. To mark a document or an ID, place a single line in the centre at 30–40%, visible without hiding the subject. Output is always lossless PNG, so a JPG source grows (compress it afterwards if needed), and every pixel outside the watermark is identical to the original.

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How to use

  1. Load the image.
  2. Enter the watermark text — a handle or account name works best.
  3. Choose the layout (tiled, centre or corner) and set size and opacity.
  4. Download; tiling at low opacity protects, a single centred line marks.

How it works

Add a watermark in three steps

Choose an image, type the watermark text (nickname, handle or site name), pick layout and opacity, press add — the result area shows the font size and mark count; download to save.

What text to use

Write "@your-handle" or your account name so reposters can trace you back; avoid phone numbers and addresses — watermarked images get shared publicly.

Tiled vs. single placement

Full-image tiling suits social photos — any cropped fragment still carries the mark; a single mark (center or corner) suits IDs and tickets that need a purpose note without covering the subject.

Opacity recommendations

For tiling use 15%-25%, faint enough not to fight the subject; for documents like "for XX use only" use 30%-40% centered — visible at a glance without hiding key info.

Code example

JavaScript Text watermark (translucent + tiled) 

// a watermark must be visible but not in the way: low alpha tiled at an angle
function watermark(canvas, text, opts) {
  const ctx = canvas.getContext('2d');
  const { size = 28, alpha = 0.18, angle = -30, stepX = 260, stepY = 180 } = opts || {};
  ctx.save();
  ctx.globalAlpha = alpha;
  ctx.fillStyle = '#000';
  ctx.font = size + 'px sans-serif';
  for (let y = 0; y < canvas.height + stepY; y += stepY) {
    for (let x = 0; x < canvas.width + stepX; x += stepX) {
      ctx.save();
      ctx.translate(x, y);
      ctx.rotate((angle * Math.PI) / 180);
      ctx.fillText(text, 0, 0);
      ctx.restore();
    }
  }
  ctx.restore();
  return canvas;                 // then export with toBlob
}

Python Tiled watermark with Pillow 

from PIL import Image, ImageDraw, ImageFont

base = Image.open('photo.jpg').convert('RGBA')
layer = Image.new('RGBA', base.size, (0, 0, 0, 0))
draw = ImageDraw.Draw(layer)
font = ImageFont.truetype('DejaVuSans.ttf', 28)

for y in range(0, base.height + 180, 180):
    for x in range(0, base.width + 260, 260):
        draw.text((x, y), 'CONFIDENTIAL', font=font, fill=(0, 0, 0, 46))   # 46/255 ~ 18%

Image.alpha_composite(base, layer).convert('RGB').save('watermarked.jpg', quality=92)

FAQ

Are images uploaded when watermarking?

No. Layout math and drawing run on the browser canvas; the photo stays on your machine from selection to download — ideal for ID photos and tickets.

Can the watermark be removed?

Tiled marks cover the whole image one strip at a time — removal means retouching every strip, which is expensive. Single marks crop out easily. For anti-theft, tile.

Why did the exported PNG get bigger?

Output is uniformly lossless PNG, so JPG sources grow. To control size, compress to JPG with the site's image compressor after watermarking.

How is the watermark's font size determined?

It starts at 6% of the image's shorter side, adjusted by text length and the size preset; the actual size shows in the result area. Presets span 60%-150%.

Can I watermark multiple images at once?

One at a time currently — swap images to continue with settings retained. Batch queues are planned; heavy users, tell us via page feedback.

Does watermarking hurt the original quality?

No. Original pixels stay untouched; the watermark is semi-transparent text drawn on top. Outside the marked areas, pixels match the original exactly — no wholesale re-compression loss.

Can I use a logo image as the watermark?

The current version supports text only; logo watermarks need alpha handling and placement details and are planned. A handle-style text watermark still identifies you fine.