Ask HN: What cool development languages/tools changed your career?

I've been a web developer for the past 10 years and I've mostly used PHP in my projects. I've also had a chance to code in JavaScript, C#, Delphi. I've had the chance to build large website (>500k users/day) and desktop apps used by millions of users per month, but I always used the technologies that felt comfortable to me. I knew Zend Framework very well, so I used that one to build the services. My "oh wow" moment was when I discovered Phalcon PHP framework (https://phalconphp.com/en/) about a year ago. I've switched all our projects on this framework and saved thousands of $$ because of the performance impact. The other thing that made my day was when I discovered Django (https://www.djangoproject.com/). I never knew Python, but I decided to give it a try. The performance is amazing (I always thought that it was slower than PHP - I was wrong) and it seems I can build the projects faster that I ever could u