Penpot is the first open-source design and prototyping tool that allows full collaboration between designers and developers. It’s the only one that can be web based or self-hosted. Penpot works with open web standards (SVG) avoiding vendor lock-in and giving teams absolute freedom in their designs. Thanks to the nature of the software that is built based on SVG standards, Penpot created the ground-breaking feature Flex-Layout, that allows you build flexible interfaces following CSS standards. Enjoy Penpot, it's free! https://penpot.app/