Skip to main content

· One min read
Carl Liu


  • Humans unite and defeat when there is a common enemy

Understanding that our identity is not fixed but is rather a collection of ideas and interpretations about who we are can give us the capacity to, when necessary, think critically about what our ego is telling us particularly when the instinct is there to preserve our identity, or ego, at all costs. The ego has gotten a lot of bad rap, but the truth is that the ego is neither negative nor positive. It is merely a sense of self that allows us to operate and function in the world, giving us an idea of who we are and where we belong. The ego is only problematic when it takes control over us rather than our true selves being in control, and when the things it tells us to do or how it is interpreting events becomes damaging to us and/or others.


· 5 min read
Carl Liu

For the past year, I have met a lot of entrepreneurs and engineers. I found a common pattern: these knowledgable people not only read more than me but are very smart in choosing the right information to read and digest.

In terms of intelligence, everyone is similar. What matters more is whether a person wants to learn/read and from which source the person learns (the information input). Just like what people always say in the gym -- 'You Are What You Eat', this applies to information and learning.

Information Hygiene 👩🏻‍⚕️

The first thing to practice is to identify the quality of information. For the modern era, a lot of online media sites and content creators tend to tune their content to maximize the impression rate or view count (if you want to learn how to write news to catch eyeballs 👁 here is a link) a better term to describe the quality of information is Information Hygiene

The following chart is my understanding of information distribution:

· 6 min read
Carl Liu

Carl: Max had an introduction tutorial session for the full stack engineers, It was really educative. Writing down this note for sharing.

Basic concepts

Mobile Linking and Mesaurement Platform

To place ads on various platforms, we need a complete system to link and measure the performance of omni-channel media advertisement campaign. Commonly used linking and mesaurement platforms are (paid) and Kochava (free). The general idea is to configure the callback URL of each advertisement delivery platform on the mobile linking platform, and at the same time embed the SDK of the mobile linking platform in the App. The platforms collect data and calculate the attribution.

· 2 min read
Carl Liu

This is an introduction blog to some knowledge (basic) and vocabs I have learnt at Presence.

App's Skill Radar

  • For any Mobile/Web/Internet startup, you need to know your advantages and disadvantages just so you don't get lured down a blind alley.
  • This is appliable not only to Mobile Apps, but also to any modern startups (i.e. Website for delivery call, aka. Doordash/Palo Altos Delivery)


  • Cost Per Install:
    • Web: 0$
  • Top tier compnay examples
    • Any web era startups: Google, Yahoo, Portal sites


  • How fast does the product spread, is it exponential or linear?
  • Top tier compnay examples
    • Uber, UberEats

Screen Time

  • How long does your user spend on your app
  • Top tier company examples
    • Tiktok -> 100 Mins
    • FB -> 45 Mins
    • Bytedance Toutiao -> 75 Mins


  • How long does a customer keep your app:
  • 2nd/7th/30th day Retention:
    • 4-2-1 -> OK (40% users kept your app on the second day, 20% users kept after a week, 10% after a month)
    • 6-4-3 -> TikTok, Facebook, Google
    • 5-3-2 -> Very good, you can go IPO
  • for Web, DAU/MAU is commonly discussed. It is the same thing as Retention
    • The formula is: DAU / MAU = 2nd day retention / 30th day retention
    • 20% -> Ok
    • 60% -> Tiktok level
    • 66% -> Facebook level
  • Top tier compnay examples
    • Tiktok, Facebook, Snapchat
    • To-B apps: Salesforce, Slack, Tableau, needed for work, mandatory retention


  • How easy is it to generate cash from your customers
  • Top tier company examples
    • Airbnb: extremely high ARPU, extremely low Screen Time
    • Amazon: Okay Screen Time, but high ARPU


  • Top tier compnay examples:
    • Apple
    • Amazon: return policy, Amazon Prime

Experiment vs. Error

· 2 min read
Carl Liu

Definition of Goals

  • Subjective vs Objective
  • Goals can be gamed by blurring its measure of success:
    • ❌Wrong: I made a good product because I think people will like it
    • ✔️Correct:
      • Physical Fact: Humans landed on the moon
      • Economic Fact: People like to pay millions of dollars for a software license per year

First Principal thinking

  • Get to the fundamentals than learning the buzz words
    • ❌Wrong: Learning definitions of Cloud, SaaS, PaaS, Metaverse...
    • ✔️Correct: Understanding FSM "finite state machine", Turning Completeness, Gödel's incomplete theorem... (This is why getting a degree in Business is so less valuable than getting a degree in Engineering. If I give you a book that has the same business strategy as Airbnb, you probably won't build another Airbnb; Whereas, if I give you a snippet of code, whether its 0 or 1, you can justify it in hours)

· 6 min read

At the end of 2021, I decided to relocate back to China due to both family and personal reasons. Extended WFH was a huge one: I was losing a ton of passion and efficiency. After evaluating a few opportunities, I decided to join Airbnb, and work out of their Beijing office!