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Advanced Concepts

Viral Loop

A growth mechanism where using the product naturally leads to inviting or exposing others who become new users.

Definition

A viral loop is a self-reinforcing growth cycle where existing users bring in new users as a natural part of using the product. Classic examples include sending a Dropbox file to someone without an account, or inviting teammates to a Slack workspace. Each new user has the potential to bring in more users, creating compounding growth.

Why It Matters

Viral loops create efficient, sustainable growth. Users acquired through viral loops have near-zero CAC and often higher engagement because they come with social context. Even modest virality (where each user brings in 0.5 new users) significantly reduces acquisition costs and accelerates growth.

How It Works

Identify actions within your product that naturally expose or involve non-users: sharing content, inviting collaborators, sending outputs, or embedding widgets. Make these viral actions seamless. Track the viral coefficient (new users per existing user) and optimize the loop. Use email to nurture viral invites and activate invited users.

Best Practices

  • 1Build virality into core product actions, not as an afterthought
  • 2Make sharing and inviting frictionless
  • 3Ensure the receiving experience is excellent for invited users
  • 4Onboard invited users with context about who invited them
  • 5Measure viral coefficient and optimize each step of the loop
  • 6Combine product virality with referral programs for additional boost
  • 7Use email to accelerate viral invite acceptance and activation

Invite Activation Emails

Nurture viral invites with targeted email sequences. Activate invited users and notify existing users when their invites convert.

Learn More

Frequently Asked Questions

A viral coefficient of 1.0 means each user brings one new user on average, creating exponential growth. Most products are below 1.0. Even 0.2-0.5 significantly helps growth. Above 1.0 is rare and powerful. Focus on improving your coefficient incrementally.

Viral loops are built into product usage. You share a document and the recipient needs to sign up to view it. Referrals are explicit asks to recommend the product for a reward. Viral loops happen naturally. Referrals require prompting and incentives.

Email activates invited users by explaining what was shared and why they should sign up. It reminds pending invites to accept. It notifies inviters when their invites convert. Email also prompts the sharing actions that kick off viral loops.