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All 12 systems · System 1

Invite loop

An invite loop turns ordinary product use into acquisition: a user shares an artifact, assigns work, or brings in a collaborator, and the recipient must enter the product to respond. It fits collaborative tools where another person improves the original user's outcome, rather than products that bolt a referral prompt onto a solitary job.

Causal engine

User completes a valuable job → collaboration becomes the obvious next step → the product sends an artifact-rich invitation → recipient can see immediate context before committing → recipient acts and reaches value → their work creates another legitimate reason to invite.

Preconditions

  • A core workflow genuinely improves when a second person views, approves, edits, or contributes
  • The inviter has already created an artifact or outcome worth sharing
  • Recipients can understand the invitation and get initial value with minimal signup friction
  • Invite, acceptance, activation, and downstream invitations are instrumented separately

Anti-patterns

  • Prompting users to import contacts before they have produced anything useful
  • Sending generic product marketing instead of showing the shared artifact and sender context
  • Counting invitations or registrations as growth while ignoring recipient activation
  • Using rewards to manufacture invites that recipients neither expect nor need

Solo-founder translation

Each week, watch five users reach the first shareable outcome, then improve one invite surface at that exact moment. Send yourself every invitation variant and remove any copy or signup step that delays the recipient's first useful action. Measure invites per activated user, invite acceptance, recipient activation within 24 hours, and the percentage of recipients who later invite someone else.

Artifact-first invite email

Artifact-first invite email

Subject

Preview text

Body

{{sender_name}} shared **{{artifact_name}}** with you and asked you to **{{specific_task}}**.

> {{one_sentence_artifact_preview}}

  1. Open the shared item.
  2. Review the highlighted section.
  3. Leave your decision or comment—no setup required before viewing.

[Review {{artifact_name}}]

This secure link expires on {{expiry_date}}. If you were not expecting it, reply to {{sender_email}} before opening.

— {{product_name}}

Instrumentation

View raw markdown
# Artifact-first invite email

## Subject
{{sender_name}} invited you to review “{{artifact_name}}”

## Preview text
Your input is needed on {{specific_task}} by {{due_date}}.

## Body
Hi {{recipient_first_name}},

{{sender_name}} shared **{{artifact_name}}** with you and asked you to **{{specific_task}}**.

> {{one_sentence_artifact_preview}}

1. Open the shared item.
2. Review the highlighted section.
3. Leave your decision or comment—no setup required before viewing.

[Review {{artifact_name}}]

This secure link expires on {{expiry_date}}. If you were not expecting it, reply to {{sender_email}} before opening.

— {{product_name}}

## Instrumentation
Track `invite_sent`, `invite_opened`, `artifact_viewed`, `recipient_action_completed`, and `recipient_activated`. Treat `recipient_action_completed`—not the email open—as the conversion.

Playbook diffs

Companies on this system

  • Calendly — Make the wedge legible
  • Figma — Multiplayer canvas invite loop
  • LinkedIn — Make the wedge legible
  • Loom — Make the wedge legible
  • Meta — Make the wedge legible
  • Miro — Make the wedge legible
  • PayPal — Make the wedge legible
  • Spotify — Make the wedge legible
  • SurveyMonkey — Make the wedge legible
  • TikTok — Make the wedge legible
  • Venmo — Make the wedge legible
  • YouTube — Make the wedge legible
  • Zoom — Make the wedge legible