Product-market fit, from the source.

The original definitions

In the glossary:Product-Market FitPivot

• The Only Thing That MattersMarc Andreessen · Pmarchive · 2007The post that made the term famous.pmarchive.com ↗
• Andy Rachleff on coining the term product-market fitAndy Rachleff · Unusual Ventures · 2020From the person who named it.unusual.vc ↗
• The Real Product Market FitMichael Seibel · Y Combinator · 2016ycombinator.com ↗
• 12 Things About Product-Market FitTren Griffin · a16z · 2017Includes Ben Horowitz's four myths.a16z.com ↗

Measuring it

In the glossary:Sean Ellis TestRetention

• How Superhuman Built an Engine to Find Product Market FitRahul Vohra · First Round Review · 2018The Sean Ellis test, run step by step.review.firstround.com ↗
• Casey's Guide to Finding Product/Market FitCasey Winters · Casey Accidental · 2021Retention as the measure.caseyaccidental.com ↗

How long it takes, and what the stages look like

In the glossary:Minimum Viable ProductEarly Adopters

• A Playbook for Achieving Product-Market Fit the Lean WayDan Olsen · The Lean Startup Co.The Product-Market Fit Pyramid, from The Lean Product Playbook.leanstartup.co ↗
• Levels of Product-Market FitFirst RoundFour levels, from nascent to extreme.firstround.com ↗
• A guide for finding product-market fit in B2BLenny Rachitsky · Lenny's Newsletter · 2023What 20+ founders said it took.lennysnewsletter.com ↗
• Demystifying the journey to PMFGaurav Jain · Afore · 2024How Knock went from idea to fit, from pre-selling to feedback loops.medium.com ↗
• How to find product-market fit: a 5 level frameworkJames Hawkins · PostHogposthog.com ↗

Founders, PMs and distribution

In the glossary:Ideal Customer ProfileCustomer Development

• Founder/market fitChris Dixon · 2011cdixon.org ↗
• “First time founders are obsessed with product…”Justin Kan · X · 2018x.com ↗
• A Dozen Things I've Learned About Marketing, Distribution and SalesTren Griffin · 25iq · 2014Source of the Peter Thiel line on distribution.25iq.com ↗
• Startups should only hire a PM once they have product-market fitBen Erez · 2024benerez.substack.com ↗
• When they hired their first PMLenny Rachitsky · Lenny's Newsletter · 2023lennysnewsletter.com ↗
• When Should You Stop Clinging to Product and Hire Your First PM?Saumil Mehta · First Round Review · 2025review.firstround.com ↗

PMF in the age of AI

In the glossary:ChurnRetention

• Insights from AI Ascent 2025Sequoia · 2025Pat Grady on “vibe revenue.”inferencebysequoia.substack.com ↗
• The SaaS Retention Report: The AI churn waveChartMogulRetention at AI-native companies.chartmogul.com ↗
• ERR vs ARR and the Conundrum of AI Revenue Streams TodayJamin Ball · Clouded Judgement · 2024Experimental revenue against recurring revenue.cloudedjudgement.substack.com ↗
• Retention Is All You NeedSantiago Rodriguez and Alex Immerman · a16z · 2025Measuring retention once the AI tourists leave.a16z.com ↗
• Product Market Fit Collapse: Why Your Company Could Be NextBrian Balfour · Reforge · 2025reforge.com ↗
• Growth lessons behind LovableElena Verna · 2025Fit as a moving target.elenaverna.com ↗
• The Internet has a second audienceMatthew Conroy · Cloudflare · 2026When the visitor is an agent.blog.cloudflare.com ↗

SF product community

• PM Social ClubSan Franciscoluma.com ↗
• ProductTank SFSan Franciscomeetup.com ↗
• Lean Product MeetupPeninsulameetup.com ↗
• Product Leadership in the Age of AIPeninsulaluma.com ↗
• Product Camp Silicon Valley 2026Product (un)conferenceluma.com ↗