Growth for Startups

What will be covered

1. Product Market fit & Retention
2. Growth channels & tactics
3. Making decisions with with A/B testing

• Most start-up doesn’t have product market fit
  • Founder believe and convince themself they do, but the truth is for most companies is not working
• Most people also believe “if you build it, they will come” but in reality: “If you build it, they won’t come”
• Important read: Do Things that Don't Scale
• Talk to your users and watch them use your product
  • What are the challenges you’re having with the product?
  • What are the things that are not working?
  • Can you show me how you use the product?
  • Fix and make the product work for early users
• Lesson: Startups take off because founders make them take off
• Typically people start with friend → friends of friends → eventually people that not your friends of friends (people that you need to reach early on)
• One way to grow when you are small: Doing things that don’t scale

Product-market fit

• How to use data (unbiased) to understand if you’ve made something people want
  • Identify the metric that represent the value my users get from my product
  • Measure the repeat usage of that metrics
  • Repeat usage are the best unbiased way to figure it out if someone liking your product
    • They might tell you things but what they do is gonna be the most important thing
• Other (worse) ways to measure PMF
  • Net promoter score - not great
  • Surveys - often biased
  • “How would you feel if you can no longer use this product”
• These are not a good metrics for PMF
  • Registered users
  • Visitors
  • “Conversion rate”
  • “Customers that aren’t paying”

Growth channels & tactics

• This section really applies if you have PMF
  • because would you work on trying to get more people to a product that no one is using your product anyway
  • Wait until we have people that care about our product
• 2 Ways to grow at scale
  • Product Growth / Conversion rate optimization
    • This mean: engineer, designer, PM and everyone working on improving specific parts of your product to get more people through that funnel
  • Growth Channels
    • platforms in the world that people tend to discover products on (eg: google, facebook, instagram)
• Conversion rate optimization
  • Your product is a funnel / growth loop
    • example: AirBnb P1 (home page) P2 (search result) P3 (Listing page P4 (Booking page)
    • Your funnel? % of people that make it from P1 - P4
    • Your job is to figure out
      • How many people make it that far?
      • Why are they dropping off?
      • What can i do to increase that number
      • Multiple teams and people at startups that work on those things
  • Every step in the funnel have drop-off
    • Every single stage in that funnel is going to have some kind of drop off for some reason
• Conversion rate optimization areas
  • Internationalization (translating it the product)
  • Authentication (make sure this flow work really well eg: Pinterest, AirBnb)
  • Onboarding (Ask how to make the experience better)
  • Purchase conversion

Growth channels to explore

• Again: don’t do this if you don’t have sense of that this is something people want
• Most new ideas are rare behavior either because they don’t exist yet or they’re not something you do every day
• Are users experience get better with more people on your product? if so do virality (eg: linkedin)
• If you don’t have people pay for your product yet skip the paid ads; you shouldn’t spending time about marketing
• Most companies grow huge using only 1 or 2 of these channels
• Tactical advice on some of the channel image above:
  • Referrals & virality
    • WOM is Airbnb largest growth driver
    • Referrals is engineered WOW
    • Good example of referral email:
  • Paid Growth
    • Don’t do paid growth if you don’t have revenue
    • CAC = Customer Acquisition Cost
    • CAC / Payback time (Most important metric in online marketing)
      • Predicted revenue must be higher than the CAC / cost
    • Attribution
    • Channels: Facebook, Instagram, Google, Youtube
  • SEO (Two main levers)
    • On-page optimization
      • Every optimization starts with keyword research
      • Which page am I trying to rank for what keyword?
      • SEO Experimentation
    • Off-page optimization
      • Who is linking to you?

Making decisions using A/B testing

• Most of you don’t need this right now (don’t do it!)
  • a/b testing calculator
  • Having 2 alternative or parallel universe at the same time then measure a metric that matter to you
  • Experiment review!
  • Place your bet!
  • Product decisions are hard (using data to make them is a good way)
  • Most of you won’t be doing A/B testing for a long time

Summary

1. Start by doing things that don’t scale
2. Measure your retention / PMF
3. Build a culture of experimentation
   • Use data and experimentation to decide what’s the best decision and not have the loudest voice in the room decide what the decision is

Notes

[1] The concept of “doing things that don’t scale” comes from Paul Graham’s foundational essay. It’s a core YC philosophy for early-stage growth: manually recruit, onboard, and delight users before trying to automate or scale.

[2] The cautionary reminder that “most startups think they have product-market fit but don’t” echoes advice from YC partners like Michael Seibel and Dalton Caldwell, who emphasize measuring user behavior over relying on surveys or NPS.

[3] The retention curve visualizations and PMF measurement tactics are drawn from YC startup school curriculum and talks by experts like Gustaf Alströmer. They emphasize usage-based metrics as the gold standard for PMF.

[4] The distinction between product growth and growth channels, as well as funnel examples (like Airbnb), are based on real-world scaling experiences from YC-backed startups and internal product teams.

[5] The advice to avoid paid marketing until you have revenue and a proven product comes from countless YC office hour sessions and case studies. Many startups fail by prematurely optimizing CAC before they know LTV.

[6] A/B testing and experimentation practices outlined here are influenced by growth leaders at companies like Airbnb, Dropbox, and Pinterest. YC generally advises early-stage founders not to start A/B testing too soon—until traffic, data volume, and product stability justify it.