Working notes from product people

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01 — TopicsFourteen drawers, sorted.

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Open drawer · 05

Building AI products

298 notes · 90 people · 2014–2026
Lenny’s Podcast116 min

OpenAI’s CPO on how AI changes must-have skills, moats, coding, startup playbooks, more

Kevin Weil · Apr 10, 2025
Key learnings
  • Build products at the edge of current model capabilities, since models improve every few months and a barely-working product can…
  • Treat evals as unit tests for models: define hero use cases, write evals for them, and hill-climb on those evals to know whether…
  • Expect AI behavior to be fuzzy: a model right 60%, 95%, or 99.5% of the time implies very different product designs, so study…
@lennysan · Lenny Rachitsky on X♥ 1,037
Trend I'm following: Teams using AI "simulations" to quickly test product ideas and flow tweaks. Products like @simile_ai, @primitivelabsai, @syntheticusers, and others. If you've tried something like this, how'd it go?
Lenny’s Podcast100 min

Jenny Wen

Jenny Wen · Mar 1, 2026
Key learnings
  • Classic linear design process (research, diverge, converge) is breaking down as engineers ship prototypes quickly; designers…
  • Design work is splitting into two modes: supporting implementation and setting a vision, where the vision now often spans three…
  • Designers can use coding tools to do last-mile polish and prototype in real code, rather than waiting on engineers for every…
Lenny’s Podcast128 min

Inside ChatGPT: The fastest-growing product in history

Nick Turley · Aug 9, 2025
Key learnings
  • Ship early to learn what people actually want; with AI, the valuable behaviors are emergent, so you won't know what to polish…
  • Treat the model itself as a product: iterate on it using real user use cases, personality/vibe checks, and new capabilities like…
  • Set the team's pace deliberately by asking whether work is 'maximally accelerated', separating fast product iteration from…
Lenny’s Newsletter♥ 839

Everyone should be using Claude Code more

Oct 14, 2025 · 20 min
Subscriber post — summary only

Lenny Rachitsky argues that non-technical people should use Claude Code, which he frames as a local-feeling AI agent that can act on files and tools on a computer. The post walks through installation steps, shows five…

@hnshah · Hiten Shah on X♥ 30
We asked Claude what changed among Linear's competitors. No skills: an old source treated as recent, and a guess stated as fact. Same model, with our competitive skills installed: every claim dated, the ranking marked as its own view, and a line about what it could not see.

02 — FrameworksModels, annotated.

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03 — PeopleWho wrote the notes.

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04 — QuestionsAnswered from the notes.

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Where notes come from

NewsletterLenny’s Newsletter106 free posts, with a longer excerpt.
Subscriber postsSummary only229 paid posts: our summary, at most two short quotes, and a link.
PodcastLenny’s Podcast322 episodes, each with 5–8 key learnings and timestamps.
EssaysSVPG · The Beautiful Mess499 essays from Marty Cagan and John Cutler.
Substack & blogsShreyas · Julie · Jason · Hiten577 essays and posts from independent writers.
XPosts on product58 posts, filtered for product relevance.