LinkedIn Growth Engine

Posted on Feb 7, 2021

Raw Notes from GrowthHackers article “LinkedIn Growth Engine: The Never Ending Viral Loop”:

  • In 2002, Reid Hoffman gathered a team of old SocialNet and PayPal colleagues.

  • Hoffman and team were all set to build a new, lasting professional network based on indentity and connections.

  • After 6 months, LinkedIn got launched on 5th May 2003.

    • After 1st week - 12.5k users
    • After 4 months - 50k users
    • After 1 year - 500k users
    • After 3 years, in 2006, they achieved profitability
    • After 8 years, in 2011, LinkedIn became a publicly traded company

Stats after 11 years (2014)

  • $18 billion market cap
  • 225 million users
  • 200+ countries
  • 4800 employees

Stats as of 2021

  • 740 million users
  • 200+ countries
  • 15,800 employees
  • 33 offices

Initial Challenges

  • Recent economic downturn (dot-com winter)

  • Difficulties in defining the core concepts of the company - a social network or something else?

How they overcame

  • Hoffman invited Silicon Valley’s successful friends and connections which quickly increased the appeal of LinkedIn.

  • Eventually, it became a must-have app for up and coming Valley workers to get connected with potential investors and advisors.

  • LinkedIn made easier for professionals to stay in touch even after changing jobs, phone numbers and email addresses.

  • Initially, LinkedIn mainly focused around the Silicon Valley. They kickstarted their network effects by tapping into a local population where it could reach critical mass.

    • Facebook did the same after 5 years later - a single school.
    • Uber did the same after a decade later - a single city.

This critical mass creates the utility needed in network businesses to create the high-quality must-have experience that breeds both user loyalty and word of mouth.


  • LinkedIn kicked off their monetization efforts with Adbrite ads in mid-2004, but unsuccessful.

  • They launched 3 lucrative revenue streams in 2005:

    • job listings
    • subscriptions
    • advertisements
  • And, just after a year, they became profitable in 2006.

Where they focused

It’s Easier to Focus on a Strength than Improve a Weakness. - Elliot Shmukler

  • 40% of signups were coming from LinkedIn Homepage (strength) and just 4% from email invitations (weakness).

    • On average, people who arrived organically visited 30 pages per session while people from invites visited just 10 pages per session.
  • Another example of focusing on strengths: “Who’s looked at your profile” emails had 20% CTR for active users and just 5% for inactive users.

    • They A/B tested subject lines, copy, and formatting of the emails only for active users which further increased the CTR.

Growth first

  • Active users play a critical role in bringing new users as well as re-activating inactive users.

  • LinkedIn’s virality was no coincidence.

  • Initially, most of the users had only 1 connection - means, they accepted someone’s invite but didn’t connect with anyone else.

    • 25% new users actually typed email addresses to invite new users.
    • LinkedIn went ahead and created an Outlook plugin which let users easily upload their email contact list to LinkedIn to find new connections. It was very unique at that time.
      • 7% users uploaded their address books and invitations sent increased by 30%.
  • LinkedIn asked all new users about their current company and title - 90% people answered this question.

    • After that they would be shown a list of people at their current company.
  • When new users sent invitation to connect, current users received notifications to approve. And, once they came on the site, they were prompted to invite and connect with others.

    • This Reconnect Flow significantly increaed virality.

      • Pageviews increased 41%
      • Searches increased 33%
      • 38% more positions listed on profiles
      • Invitations increased 16%

New users invite more new users and engage old users. And, then old users invite more new users. - That’s double viral loop.

  • LinkedIn introduced Endorsement feature which further re-engaged inactive users.

This way, re-engaging inactive users is both less expensive than ads and more effective than reactivation emails.

  • LinkedIn made profiles public which brought a lot of traffic from search engines.

  • They waited until 2 million users before user profile indexing.

    • When people clicked on someone’s profile from search engine, they had to sign up to connect with the person.


  • LinkedIn acquired Gmail plugin Rapportive for $15M which lets users connect with their contacts on LinkedIn [Feb 2012].

  • Because presentations are important for professionals, LinkedIn acquired SlideShare for $119M [May 2012].


  • In 2011, they launched LinkedIn Today which culled articles that a user’s coworkers and industry peers are sharing.

  • Users could also share and comment on those articles.

  • In 2012, LinkedIn launched an Influencer program which allowed selected thought leaders to create original exclusive contents and users could just follow without getting connected to them.

  • The influencer program is not just good for LinkedIn but for the influencers too.

    • 22% influencer followers are entry level professionals
    • 49% are director-level or above


  • 41% of LinkedIn traffic comes from mobile devices.

  • In 2013, they launched a new app called LinkedIn Intro which allowed users to LinkedIn profiles right into the iPhone Mail App.

    • Means, if someone receives an email from unknown sender, they will also be able to see their LinkedIn profile.