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Technique · Hooked

Invites that carry value to the person invited

Design normal use so it sends something useful to people who aren't users yet: a payment, a shared file, a finished result. The recipient gets value on first contact, and the sender's output carries a light, honest attribution.

Evidence grade C. Limited evidence: few or small studies.DiscoverSpread

Plain label: value-carrying invitesAlso known as: PayPal pattern, product-led invites, shareable output, relationship trigger, share card, collaborative invite

How it works

Relationship triggers spread fastest when the invitation itself is worth opening, because acting on it serves the recipient. Output that users are proud of travels to other networks and prompts friends to try the product. Tricking users into inviting spends their goodwill with friends and ends in backlash.

Evidence warning

Sending invitations or reminders in a user's name without per-message consent ended in a $13M settlement for one professional network (2016).

What the research says

  • In the late 1990s, receiving money was reason enough for recipients to open a payments account (book account).

    Hooked Ch.2 (PayPal)

Before you start

  • At least one segment already has product-market fit.

How to build it

B2B
Shared dashboards, documents or reports open without an account, with a clear way for the viewer to start their own.
Mobile
One-tap share of a finished result card with a small attribution link the user can edit.
E-commerce
Gift links and shared wishlists the recipient can act on without signing up.
Web
Invites name the person and the item ('Ana shared a board with you') and land on that item.

What can go wrong

  • Pre-checked invite-all or contact scraping.
  • Invites that carry an ask but no value.
  • Attribution so loud it embarrasses the sender.

Pairs well with

  • Ask for shares right after a win.
  • Measure recipient activation, not invites sent.

In practice

Where it shows up

  • Dropbox · 2010

    Dropbox: a referral reward that is the product

    Sign-ups reportedly about 60% higher with two-sided storage rewards, and about 2.8M referral invites in one month of 2010 (secondary sources; grade D). Retellings disagree on the endpoints, so avoid the “3,900% in 15 months” headline.

    M3 ×Spread
    Case grade for the number: D. Evidence grade for the mechanism link: D.Anecdote

  • LinkedIn · 2015

    Round

    LinkedIn: invitations sent in your name

    Perkins v. LinkedIn: a $13M settlement announced in Oct 2015 (final approval in Feb 2016) for Add Connections users from Sept 2011 to Oct 2014. The suit alleged members agreed to the first invitation but not the two reminder emails. LinkedIn denied wrongdoing.

    M3 ×Spread
    Case grade for the number: A. Evidence grade for the mechanism link: C.

  • Spotify · 2025

    Round

    Spotify Wrapped: identity as a reward

    200M+ engaged users in the first 24 hours of Wrapped 2025, 19% more than 2024 (which took 62 hours to reach 200M), and 500M+ shares, up 41% (Spotify, via TechCrunch, Dec 4, 2025). Company-reported.

    M4 ×ReturnSpread
    Case grade for the number: B. Evidence grade for the mechanism link: D.Analyst inferenceCompany-reported

Limits

What we don’t claim

  • The Hook Model is a practical design tool, not a validated or complete theory of behavior.Hooked, Introduction
  • Left Brain and Right Brain are a metaphor for extrinsic and intrinsic motivation, not a claim about neuroscience.Actionable Gamification Ch.13, pp.342-343

Sources

  • Hooked · Nir Eyal

    Ch.2 · Ch.7

Source IDs: HK-TRG08HK-TRG09HK-RWD09

Book content is paraphrased, never quoted at length. Last verified October 24, 2026.

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