I’m only posting this because I’ve seen official balsamiq blogs link to other software products.
The intention here is to link to complementary software, not competing
I would like to mention these little tools I use on Windows:
Monosnap (Windows/OSX - https://monosnap.com)
Similar to the built-in Windows Snipping Tool but with more functionality and extremely easy to use.
If you configure it with a login account, and alter the default capture actions, you can make it upload your image and copy a link to the URL to you clipboard for linking online (images are eventually deleted, but has never been a problem for me). But it’s also great for capturing a small part of your mockup, annotating it and sending to colleagues.
Pixie (Windows http://www.nattyware.com/pixie.php)
All it does is display the exact colour notation for where your cursor is positioned, so that you can match it in balsamiq or another application.
f.lux (Windows/OSX/Linux https://justgetflux.com/)
If working late at night, it softens the screen making it much easier to work longer and get to sleep quicker when you’re done. Takes a week or two to get used to the orange colour shift, but I can hardly use a PC at night without it now. You will want to disable it if choosing colours accurately, which is easily done.
I have no affiliation with any of these apps, and they’re all free.
I invite others to add your favourites below.