Free Online Resources I Use As A Freelance Web Designer

Google Speed Test
If your page is running slow, Google Speed Test pinpoints exactly what it is that is causing that reduction in speed.

This peed test tool shows you detailed information about all the content on your site and how it affects speed.

Browserstack allows you to see what your site looks like on various platforms and  browsers, (like safari, firefox, chrome, iphones, aesus, pc, etc.)

Paletton calculates the exact colors that compliment your color of choice. It’s very useful for finding colors that work well with one another.
Optimize the size and download speed of PDF’s.  This website also has conversion tools like PDF to JPG or PDF to Word document.