Financial Expertise That Fuels Growth

At Open Book Partners, we don’t just manage numbers—we unlock financial potential. As your trusted outsourced CFO, we bring clarity, strategy, and execution to your financial operations, empowering businesses to scale confidently. From financial modeling to fundraising and investor relations, our expertise ensures you have the insights and structure needed to thrive in today’s fast-moving economy. Whether you're preparing for your next funding round or optimizing your cash flow, OB Partners is here to guide you every step of the way.

Meet The Founder

Harry O’Sullivan

Founder & CEO

CFA, CPA

Harry leads OB Partners, helping startups secure funding, build financial models, and scale strategically. With over a decade of experience, he has raised over $70M for high-growth companies.

Our Values

At OB Partners, we believe that financial strategy should be more than just numbers—it should be a roadmap for sustainable growth. Integrity, transparency, and innovation drive everything we do, ensuring our clients have the tools and insights to make bold, data-driven decisions. We operate as an extension of your team, bringing world-class financial expertise tailored to your unique challenges. Our mission is simple: to help businesses navigate complexity, unlock opportunity, and achieve financial excellence.

Integrity

People

Velocity

Flexibility

Vision

This Is Us In Numbers

$100M+

Raised in client venture capital & debt

30+

Startups and growth-stage companies partnered with

10+

Years of Industry Experience

Average revenue growth