Sigurjón Ísaksson Appointed as Chief Technology Officer of Definely: A New Era in AI Legal Tech

Definely has named Sigurjón Ísaksson as its new Chief Technology Officer (CTO), underscoring the company’s ambition to scale its AI-powered legal technology and deepen its focus on advanced contract drafting and review solutions. His appointment comes as legal teams worldwide accelerate adoption of specialised AI tools that streamline complex documentation while maintaining high standards of accuracy and compliance.

Sigurjón Ísaksson’s Journey in AI and Product Building

Sigurjón Ísaksson brings a rich mix of hands-on machine learning experience and startup leadership to Definely’s executive team. Early in his career he worked as a machine learning engineer, contributing to applied AI projects that demanded both technical rigour and a strong product mindset. He later co-founded Nosso, a fintech startup designed around long-term, family-focused financial planning, where he helped shape both the product and the underlying technology stack in a fast-moving environment.

In 2024, Ísaksson joined Definely as Head of AI, a role that placed him at the centre of the company’s push into next-generation, AI-native tools for contract analysis. During this period, Definely continued to attract attention as a fast-growing legaltech company, recognised in rankings such as Deloitte’s UK Technology Fast 50 and Sifted’s lists of high-potential tech firms. His leadership across AI research, engineering, and product integration laid the groundwork for his elevation to CTO at a time when the company is in a high-growth, post-Series B phase.

Responsibilities as Chief Technology Officer

As CTO, Ísaksson now oversees the full breadth of Definely’s technology roadmap, from core platform engineering to experimental AI initiatives. His remit includes leading product development for the Definely Suite and its AI extensions, ensuring that each new capability fits seamlessly into the workflows of law firms and in-house legal teams that rely on the platform for high-stakes contract work.

He is also tasked with building and scaling a high-performing engineering and data science organisation that can move quickly without compromising on reliability or security. That means strengthening technical ownership, formalising processes for secure AI deployment, and maintaining the performance and robustness of a platform used by major firms and corporate legal departments worldwide. In parallel, Ísaksson is expected to drive innovation around explainable, domain-specific AI so that lawyers can trust system outputs and trace how recommendations are generated.

Advancing Definely’s AI Product Portfolio

Definely has spent the past several years building a specialised AI stack for legal documents, with two flagship offerings at the centre of this strategy: Enhance and Cascade. Enhance is positioned as an AI contract analysis layer embedded in Microsoft Word, enabling lawyers to draft, review, query, and summarise complex agreements directly within their existing environment, supported by an agentic AI system tuned on legal data. Cascade complements this by helping users understand knock-on effects across contracts, flagging dependencies and downstream changes when key terms are updated.

These products are designed to reflect how legal professionals actually think about contracts, focusing on structure, defined terms, and cross-references rather than treating documents as generic text. Under Ísaksson’s leadership, Definely intends to extend this foundation into more end-to-end workflows, from first-draft generation through review, risk analysis, and finalisation, with AI assisting at each step while preserving human control. This approach aligns closely with wider industry demand for tools that can compress review cycles, reduce manual errors, and surface insights that are difficult to track in traditional, document-heavy processes.

Leadership Backing and Strategic Momentum

Definely’s leadership team has publicly emphasised the importance of continuity in its AI strategy, which makes Ísaksson’s move from Head of AI to CTO a natural progression. CEO Nnamdi Emelifeonwu has highlighted the impact of the AI organisation’s work on products like Enhance and Cascade, which are now used by over 100 law firms and corporate legal teams, including Magic Circle firms and global enterprises. Keeping the architect of that AI roadmap at the helm of technology is intended to preserve momentum as the company scales into new markets and customer segments.

This appointment also sits against the backdrop of Definely’s substantial funding activity and international expansion. In a Series B round completed in 2025, the company raised around 30 million dollars (approximately 22 million pounds), backed by investors including Revaia, Alumni Ventures, Beacon Capital, Clio, Octopus Ventures, The Raine Group, Zrosk Investment Management, and Cornerstone VC. The fresh capital is being directed toward accelerating AI product development and strengthening Definely’s presence in key markets such as the United States, reinforcing the need for a CTO deeply versed in both AI and product scaling.

AI’s Expanding Role in Legal Workflows

Legal teams globally are under pressure to deliver faster, more accurate work while managing increasingly complex regulatory and commercial environments, which has created strong tailwinds for specialised AI tools. Definely’s focus on human-first, explainable AI reflects a broader shift away from generic productivity tools toward domain-specific systems that can handle nuance, context, and the high stakes of contract interpretation. As CTO, Ísaksson will be central to translating advances in machine learning into concrete capabilities that fit the way lawyers work, from clause-level analysis to portfolio-wide risk assessment.

For organisations adopting AI in legal operations, this kind of product leadership helps bridge the gap between innovation and practical deployment at scale. The combination of Definely’s funding, its expanding customer base, and a sharpened technology vision gives the company a solid platform to shape the next wave of AI legal tech, where trusted, workflow-native tools become a core part of everyday legal practice rather than optional add-ons.