Over the last 8 years I've tried out a lot of different tools, resources, and approaches to the process of designing user interfaces and experiences. Here's what I'm currently using on an almost-daily basis. If I happen across something else that I feel is list-worthy, I'll be sure to update the post. :)
Adobe CC (XD, Illustrator, Photoshop): Good ol' Adobe. My UI/UX adventures began with Photoshop and Illustrator in 2012. They worked alright for me but the process felt cumbersome. Thankfully, Adobe introduced XD a couple years ago as their solution for designing interfaces. Compared to what I was doing in Photoshop back in 2012, XD is AMAZING. Having an app dedicated to UI design makes such a big difference in process, design and deliverables. I still use Photoshop for preparing image files for use online. I use Illustrator for designing and making icons (one of my favorite things to do). For UI/UX design it's all XD.
Webflow: I LOVE Webflow! After discovering Webflow it became my go-to application for prototyping until XD came along. However, I am still a big advocate of Webflow and the "no code movement" and use it nearly every day to manage my websites. The three reasons I love Webflow for prototyping are: 1) It's very easy to design and build responsive prototypes. 2) You build the prototypes using the same techniques and concepts as a developer would use (just through an interface). 3) The ability to export your code to hand off to the developer saves time and helps with communication. Because of what I learned using Webflow, I am now able to speak the same language as developers regarding UI.
Google's Material Design: I think of Material Design as a style guide for the web. I have some differences in opinion regarding some things, but it is an invaluable resource when it comes to understanding components, designing toward accessibility requirements, and keeping up-to-date with web design standards.
Zeplin: I was recently introduced to Zeplin through a project and though I have yet to discover all that it can do, I've found it to be very useful for providing specs and assets to developers one screen at a time.
Also worth mentioning:
Figma: I haven't used Figma for a project yet, so my opinion isn't worth much. All I'll say for now is that Figma is on my radar because of its collaboration functionality and because it's browser-based.
Sketch: I think Sketch is the reason Adobe built Adobe XD. It's a great app and currently the industry standard for UI/UX design.
I found out about a lot of these tools by reading TechCrunch every day. It has been a great way for me to find out about product announcements or public beta programs. Definitely worth checking regularly.