If you want to quickly add a watermark on a single photo and don't want to install a software just for that, you can use a free online photo watermark app uMarkOnline.com.
uMark Online is an online version of uMark, the best batch photo watermark software for Windows and Mac.
Adding watermark to a photo on uMarkOnline.com is very easy. You just need to upload the photo and set a watermark text. uMarkOnline automatically calculates the optimal size of the watermark but you can change it to your taste. You can select choose a font, color and transparency level for your watermark. You can place your watermark on one of the 9 predefined positions. Once you are done creating your perfect watermark just right click on the image and save the watermarked photo on your computer.
uMarkOnline.com will work in any browser like Firefox, Chrome, Safari, Internet Explorer and even your iPad, iPhone and Android browsers.
Adding a caption on a photo, online for free has never been this easy!
Check out uMarkOnline.com.
For Windows and Mac. Available in 8 languages - Dutch, English, French, German, Italian, Portuguese, Spanish and Turkish.