Unrelenting: How the Toss Team Broke Boundaries

What This Book Is About
UNRELENTING tells the true story of Toss, a Korean fintech startup that transformed how people send and receive money. But more importantly, it's a story about people-35 team members who dared to question the inconveniences we've learned to accept and built something extraordinary in response.

Beginning in 2011 with a single audacious question-"Why is sending money so difficult?"-this book chronicles Toss's eleven-year journey through eight consecutive failures, regulatory battles, and moments of breakthrough that would reshape Korea's financial landscape. From the humble coworking spaces of early 2015 to the regulatory triumph of becoming the nation's third internet bank, UNRELENTING captures the raw, unpolished reality of building something that matters.
Why Read This Book?
For entrepreneurs and founders: A masterclass in persistence. Learn how Toss navigated regulatory hurdles, pivoted business models, and maintained conviction when the path forward seemed impossible.

For business leaders: Insights into building a high-velocity organization driven by clear purpose, radical honesty, and a commitment to doing the hard work that others avoid.

For anyone interested in innovation: Discover how technological innovation intersects with regulatory policy, customer psychology, and human ambition in the real world.

For readers of company histories: An unflinching look at what it actually takes to build a global fintech unicorn-the victories and the setbacks, the brilliant ideas and the near-fatal mistakes.

KEY THEMES
V Boundary Breaking: How a startup challenges the financial establishment and wins

V Radical Honesty: The role of transparency and accountability in driving exceptional teams

V Iteration and Failure: Eight failures that ultimately led to one defining success

V Cultural Leadership: Building a team culture centered on ambitious goals and relentless execution

V Regulatory Innovation: Navigating Korea's financial system to create solutions that were never before possible

V Customer-Obsessed Design: Making complex financial services genuinely simple and accessible

Prologue

To readers far away

Chapter 1. The Courage to Cross the Line
- The beginning of a journey
- Wanted by no one in the world
- Ghost protocol
- Shutdown

Chapter 2. Careful, but Ruthless
- All set to bring you in
- Official launch
- Born into competition
- A collapsed revenue model
- Beyond transfers, toward a financial platform
- And so we fail-only to succeed in the end

Chapter 3. The World's Fastest-Growing Startup
- Tears shed in Silicon Valley
- A rush of account closures
- Bold in ambition, dadadada in execution
- The positive impact of a financial platform
- Growing pains

Chapter 4. Why Road Bikes Are Uncomfortable
- The hidden cost of speed
- Horizontal innovation
- Epic growth
- Becoming a unicorn

Chapter 5. A Sign of a Great Undertaking
- Reclaiming our vigor
- The scale-up strategy
- The stage is set
- Charting its own course
- Trust as an asset

Chapter 6. Innovation: No Beginning, No End
- The long-awaited future
- A bank for more people
- Dreaming beyond boundaries
- The hypothesis remains unproven

Epilogue
Endnotes

Kyounghwa Jung Kyounghwa Jung is the Head of Brand at Toss and a former journalist. After joining Toss in 2020, she recognized that the company's story-one of relentless pursuit, strategic ambition, and human determination-needed to be told with the nuance and depth it deserved.

Moving between the perspectives of insider and observer, Jung spent over a year conducting extensive interviews with 35 current and former team members, supplemented by company archives, emails, and personal accounts. She believes that records firmly grounded in reality carry lasting power.