Free batch image watermarking software [closed]

"XnView can do this, with the batch processing feature.

You select which pictures to transform, from where to where, in which format, and which action(s) to apply to them, including adding a watermark.

And it's free!"

I did this for about 6000 photos using FastStone Image Resizer. Also lets you save profiles so you can run it again on additional batches.