Lenny's Podcast: Product | Career | Growth

Slack founder: Mental models for building products people love ft. Stewart Butterfield

November 20, 2025

AI Summary

5 min read

Stewart Butterfield shares mental models from founding Flickr and Slack, emphasizing relentless product improvement, user comprehension over friction reduction, and organizational discipline to deliver customer value.

Utility Curves for Feature Decisions

Butterfield describes utility curves as S-shaped graphs where initial effort yields little value, a middle steep rise delivers most gains, and further investment hits diminishing returns. For features like a hammer's durability or an app's search, teams assess position on the curve to avoid half-built additions that add complexity without payoff. He layers on "divine discontent," noting standards rise with familiarity and competition, requiring ongoing iteration on core flows like login or checkout, as seen in Google Calendar's poor time zone picker despite massive usage.

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What you'll learn

1 `* (00:00:14) **Launch Reflections & Core Principles**`
2 `* (00:02:27) **Current Life & Prep Insights**`
3 `* (00:06:10) **Utility Curves Framework**`
4 `* (00:11:22) **Delight, Craft & Taste**`
5 `* (00:20:37) **Slack Craft Examples**`
6 `* (00:28:31) **Friction vs. Comprehension & Don't Make Me Think**`
7 `* (00:46:31) **Divine Discontent & Organizational Challenges**`

+ Full timestamped outline available in the app

Show Notes

Stewart Butterfield is the co-founder of Slack and Flickr, two of the most influential products in internet history. After selling Slack to Salesforce in one of tech’s biggest acquisitions, he’s been focused on family, philanthropy, and creative projects. In this rare podcast appearance, Stewart shares the product frameworks and leadership principles that most contributed to his success. From “utility curves” to “the owner’s delusion” to “hyper-realistic work-like activities,” his thoughts on craft, strategy, and leadership apply to anyone building products or leading teams.

We discuss:

1. Hyper-realistic work-like activities

2. The owner’s delusion

3. Utility curves

4. “Don’t make me think”

5. “We don’t sell saddles here”

6. Tilting your umbrella

7. When to pivot

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