Sketch: Our go-to design tool

https://www.sketchapp.com/


Invision: Tool to share designs and create prototypes (25$/month)
https://www.invisionapp.com/


Avocode: Tool for the front-end guys to inspect the designs (243$/Year)
https://avocode.com/


Nucleo: icon management 49€ (one time, optional 49E a year updates we currently don't use)
https://nucleoapp.com/


Other popular tools

Balsamiq:

Quick wireframes/mockups.

Gliffy: Gliffy Online wireframe/work-flow diagram and mockups tools

https://www.gliffy.com/

Figma: Sketch+Invision+avocode in one, both web and native apps.