Give it the Craigslist test

Apr 10, 2023


4D Thinking kit
4D Thinking kit
4D Thinking kit

It’s never been so easy to create incredibly polished mockups — from design software upgrades to AI assistants, we’re seeing usable user interfaces come to life in seconds.

But there are some major business risks in this approach. They can burn you even if you’re a team who makes time for user research.

  1. The aesthetic-usability effect — People perceive more aesthetically pleasing interfaces as more intuitive or usable (whether they are or not). User research participants will pick the prettiest option, or tell you they love a beautiful mockup even if it’s difficult or low-value.

  2. Parkinson’s law of triviality — People get overwhelmed by big decisions, and so they spend disproportionate time on small ones. User research participants (and designers) love to focus on fun elements like colors and interactions, and don’t get around to the larger questions of why and when the product is needed.

Look at Maybe, a gorgeous financial services dashboard that announced a big pivot today because “six weeks after launch, we only had 50 paying customers, out of a waiting list of 10,000+ people.”

So. If you’re designing a new product or service, give it the Craigslist test — start with low-fidelity options that see if people would love it even if it looked like Craigslist.

Low-fidelity (shown in my UX sketching kit image above) means:

  • NO: styling, photographs, illustrations, colors, or fonts (besides a default one)

  • YES: real text (not lorem ipsum), symbolic images, and symbolic UI

Focus on content and functionality when you’re designing new products; that’s the validation that will build a business.

UPDATE: A couple clarifications, since this post spent a few days on the home page of Hacker News and inspired some discussion there:

  1. I’m not saying your product needs to look like Craigslist all the way up until the end, just that it’s a key test in early stage concept validation. Yes, later on, once VALUE is proven, by all means consider design polish to make the experience even better!

  2. This idea is not unique or brand new (I’m an old Balsamiq fan, Basecamp fan, etc) — the post is just a direct response to the increase in AI-generated interface mockups, trying to get people to think a bit more deeply about those.

This post draws from the ideas in my book Think in 4D. Subscribe for more at

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