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SlimFile

Watermark images

Stamp your name, a copyright line or DRAFT across a batch of pictures. Corner, centre, or tiled over the whole thing.

Position
Colour

Choose your images

up to 20 at a time.

JPGPNGWebPAVIFHEICGIFMax 15 MB each

  1. Write your text

    Then choose where it sits, how big it is and how strong it looks.

  2. Drop your images

    Up to 20 at a time. The text is sized relative to each image, so a mixed batch comes out consistent.

  3. Download

    One at a time, or the whole batch as a zip.

Sized to the picture, not to the pixel

The text height is a share of each image's shorter edge rather than a fixed number of pixels. Drop a phone photo and a thumbnail into the same batch and the watermark looks the same size on both, instead of covering one and vanishing on the other.

White text carries a faint dark shadow and black text a light one, so it stays readable over a bright sky or a dark jacket rather than disappearing into whichever it lands on.

Results come back as PNG so the text stays crisp. A watermark is not security — anyone determined can crop or paint it out — it marks ownership and discourages casual reuse. Tiled is the hardest to remove cleanly.

Why use SlimFile for this

  • Consistent on every photo

    The text is sized from each picture, so a big phone photo and a small thumbnail get the same proportion.

  • Readable on light and dark

    A faint shadow keeps the text visible over a bright sky or a dark jacket.

  • Free, no sign-up

    No account, no email address, no trial that runs out.

  • No watermark

    What you download is clean — nothing added to your file.

  • Deleted within an hour

    Uploads and results are removed automatically about an hour after processing. We never look inside them.

Questions

How do I add a watermark to many photos at once?
Add up to 20 images, type your text, choose corner, centre or tiled, and download them all as a zip.
Will the watermark be the same size on every photo?
Proportionally, yes. The text height is a share of each image shorter edge rather than a fixed number of pixels, so a large phone photo and a small thumbnail come back looking consistent instead of one being covered and the other showing nothing.
What if my photos are light in some places and dark in others?
White text carries a faint dark shadow and black text a light one, so it stays readable over a bright sky or a dark jacket rather than disappearing into whichever it lands on.
Does a watermark protect my photos?
Not really, and it is worth being honest about it. Anyone determined can crop a corner mark off or paint it out. A watermark marks ownership and discourages casual reuse — tiled across the picture is the hardest to remove cleanly, at the cost of being more intrusive.
Why do I get a PNG back?
So the text edges stay crisp. Saving as JPG would re-compress the whole picture and soften exactly the part meant to stay legible. Run the result through Convert Image if you need a JPG.

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