At this moment Zuul web interfaces displays output of commands as raw, so any ANSI terminal output will display ugly artifacts. I tried enabling ANSI about half a year ago but even after providing two different implementations, I was not able to popularize it enough. As this is a UX related feature, I think would like more appropriate to ask for feedback from openstack-discuss, likely the biggest consumer of zuul web interface. Please comment/+/- on review below even if you are not a zuul core. At least it should show if this is a desired feature to have or not: https://review.opendev.org/#/c/739444/ ✅ This review also includes a screenshot that shows how the rendering looks (an alternative for using the sitepreview) Thanks Sorin Sbarnea