Website Grader - Grade your website's strengths and weaknesses in seconds.
UserTesting.com - Usability testing has never been easier. Get videos of real people speaking their thoughts as they use websites, mobile apps, prototypes and more!
Checkbot - Checkbot will boost the SEO, speed and security of your site by checking you're following 50+ web best practices. Browser extension with free and paid plans.
Userbrain - Easy, fast, and affordable user testing for websites and prototypes.
PageSpeed Ninja - One-click page speed boost for WordPress
userinput.io - Get on-demand feedback for your app, website or idea. Learn how to improve by hearing real opinions.