Definely appoints Sigurjón Ísaksson as Chief Technology Officer

LONDON 14th January 2026 - Definely, an AI-powered legaltech company that allows lawyers to efficiently and accurately review complex contracts, has appointed Sigurjón (Sjonni) Ísaksson as Chief Technology Officer (CTO), effective immediately.

Ísaksson’s appointment comes after a landmark year for Definely, including the close of a $30m Series B, expansion into North America, and multiple product launches. Sjonni joined Definely in 2024 as Head of AI and led the development and release of Definely  ‘Enhance’ and ‘Cascade’. These two new products transformed Definely’s AI capabilities, shaping its agent architecture and integrating with the products that power Definely’s tech stack.

Sjonni has nearly a decade of experience as a Machine Learning Engineer, conducting research and developing applications for global corporations. Prior to joining Definely, Sjonni was the CTO and Co-Founder of Nosso, a consumer fintech business that helped families invest more collaboratively. His ability to build and scale specialised AI products from the ground up provides the foundational leadership and technical expertise required to lead a high-growth legal tech team as CTO of Definely.

Definely is built for lawyers working under pressure on complex, high-stakes deals. It meets lawyers where they are by integrating within Microsoft Word, rather than operating on a separate system or platform. Definely provides out-of-the-box solutions for lawyers to solve existing workflow challenges. This increases the quality and efficiency of using Gen AI products and the overall value to a law firm or in-house legal department.

As CTO, Ísaksson will continue to lead Definely’s product development, building on its underlying technologies that solve complex workflows for legal professionals. Definely will also be scaling its technical department, with planned investment into AI engineers to further develop Definely’s technology capabilities and product scope.

Sigurjón Ísaksson, Chief Technology Officer of Definely, says: “2025 has shown that Definely’s AI offering is uniquely positioned within a crowded market, and the customer success speaks for itself. I have spent the last two years developing first-of-its-kind AI solutions for complex contract reviewing, unifying Definely’s existing product stack to solve end-to-end workflows for lawyers, and I look forward to doubling down on this as CTO. I am excited to lead an incredible tech team and push the boundaries of deep AI innovation we have achieved in 2025 ”

Nnamdi Emelifeonwu, Co-Founder & CEO of Definely, says: “Sjonni has already proven what he can do at Definely. As Head of AI, he led the development and launch of Enhance and Cascade, products now trusted by law firms and in-house legal teams around the world. Appointing him as CTO gives us continuity and real momentum: faster shipping, stronger technical ownership across both AI and platform, and a clear focus on scaling reliability, security, and enterprise readiness as demand accelerates. Just as importantly, Sjonni is building the kind of high-performing engineering organisation that will help us deliver consistently as we grow.”

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