This chapter examines the critical role of contracts and commercial agreements in establishing a secure and scalable foundation for FinTech startups. It outlines the essential legal documents required, including shareholder agreements, investor agreements, employment contracts, customer terms, and partnership agreements. The chapter then delves into the specifics of technology and licensing agreements, highlighting key components and negotiation strategies. A major focus is placed on data privacy and security provisions within contracts, with a comparative analysis of regulatory approaches under the GDPR (England and Wales), CCPA (United States), etc. Finally, it addresses best practices for drafting and managing vendor and supplier agreements to mitigate risk and ensure operational resilience. The overarching theme is that well-crafted contracts are not merely formalities but vital tools for protecting intellectual property, ensuring regulatory compliance, managing relationships, and facilitating the long-term growth of a FinTech venture.