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How David Sinkinson Bootstrapped AppArmor to a $40M Exit (Avoiding a Costly Negotiation Mistake)

David Sinkinson

In this week’s Built to Sell Radio episode, John Warrillow interviews David Sinkinson, co-founder of AppArmor.

David and his brother Chris created a mobile app that allows students to alert campus security by pressing a single button on their phones.

Their journey from developing AppArmor to selling their company for $40 million is packed with insight. 

During the interview, you’ll discover how answering a simple question posed by an acquirer almost cost the Sinkinson brothers $20 million.

Learn how they navigated this near-disastrous moment and what steps they took to recover and close the deal successfully. 

In this episode, you’ll also learn how to: 

  • Dodge the question that almost ended up costing David $20 million. 

  • Turn your customers into raving fans. 

  • Unlock the hidden strategy that helped AppArmor fund its growth without outside investors. 

  • Transform one-time app users into dedicated, recurring customers with one simple tactic. 

  • Master the negotiation techniques that secured AppArmor’s $40 million exit. 

  • Achieve an incredibly low customer churn rate with this unexpected approach. 

  • Strengthen your co-founder relationship using the Sinkinson brothers’ key insights. 

Listen Now

About David Sinkinson

David Sinkinson is the co-founder of AppArmor, a company developing custom-branded safety apps and emergency notification systems. Founded in 2011, AppArmor was acquired by Rave Mobile Safety this year.

David’s journey began while working at his alma mater, Queen’s University, where he identified gaps in campus safety and pitched the idea of a custom-branded safety app.

This initiative led to the creation of AppArmor, which now helps keep millions of people safe during crises. Before AppArmor, David worked at a major telecommunications firm in Canada, launching customer-facing marketing retention projects.



This is a comprehensive appraisal of a business or investment undertaken before a merger, acquisition, or investment. It seeks to validate the information provided and uncover any potential risks or liabilities.


This is a financing arrangement for the purchase of a business, where the seller must meet certain performance goals before receiving the full purchase price. It reduces the buyer’s risk and aligns the interests of both parties post-acquisition.

Letter of Intent (LOI):

This document outlines the basic terms and conditions of a deal before a formal agreement is drawn up. It serves as a mutual commitment between the buyer and the seller to move forward with the transaction on the agreed-upon terms.



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