Redesigning for millions of users

by Shareef Ayyad. Average Reading Time: almost 2 minutes.

In his talk at UX London, Aarron Walter explains how MailChimp redesigned their interface from the ground up, despite having over 5 million users.

  • When you redesign a system, often it’s the pro-users that suffer due to their muscle memory interactions
  • MailChimp had technical debt dating back to 2001
  • There was also a shift in user behaviour – a need for access on mobile devices
  • Performed lots of research on which devices and their contexts of use
  • Used findings as a springboard to watch users using MailChimp
  • Found they no longer used the system in a static place (i.e. cubicle desk at work)
  • Mobile devices were not eating desktop usage, but extending it
  • Forced design team to rethink assumptions

Creating a vision

  • Hired actors and wrote a script. Produce an internal video of ideal MailChimp user scenarios. Used as a vision for company
  • Video showed user starting email campaign on desktop, moving to mobile, receiving feedback from team members
  • Video demonstrated teamwork over many devices

Design process

  • Was confusing and daunting at first.
  • Started with small units of interface but quickly realised it would be a massive change
  • Had to choose whether new app would “work differently but feel same” or “feel different but work same”
  • They were iterating like mad. Had to stop and choose one to build and test.
  • Divided the problem down to its smallest units. Tackled them one-by-one
  • Developed a pattern library – styles, grid system, animations, example code snippets (ux.mailchimp.com)
  • They printed every page out so everyone in company could add notes and scribble annotations
  • Created collective ownership.
  • UI printed on paper gave a fresh perspective to designs
  • Changed layout of office to bring designers/devs/QA/marketing together to talk and brainstorm
  • This built energy, excitement, camaraderie


  • Launching is just as scary as redesigning from scratch
  • Needed to communicate to 5 million users that a change was coming
  • Wrote blog posts and emails to users justifying redesign
  • Soft launch with a modal window giving users a choice whether to try new interface
  • “You may” instead of “You must” is better psychologically

Feedback and iteration

  • Categorised feedback based on personas
  • Shifted to faster release schedule (2 week sprints)
  • Devised a mantra – “listen hard, change fast”

Further reading