Senior Frontend Developer

* You must have the right to work in the location you're applying for - no visa sponsorship can be provided.

Cornspring is an innovative start-up FinTech company, with a mission to empower Family Offices and Asset Owners with real-time, AI driven data intelligence and portfolio insights.

The tools we are building are solving one of the most complex and valuable challenges in Finance.

Our clients operate at the highest levels of global finance, managing billions in assets. Yet, legacy systems fail them: slow, fragmented, and outdated. Cornspring is redefining Family Office services by leveraging state-of-the-art generative AI and Large Language Models to provide unparalleled insights and efficiency to Family Office investment and accounting data.

We are growing fast, and we need exceptional engineers who bring a mix of talent and passion to join us on our incredibly exciting journey to help us develop the company further.

Cornspring is a collaborative and high-ownership start-up environment where innovation is at the core of what we do, offering you some incredible learning opportunities.

We are currently looking for a top-tier Frontend Developer who thrives at the intersection of elegant UI development and advanced Excel Add-in engineering.

You would be reporting to the Head of Platform Development and would be working alongside a team of high-calibre, mission-driven engineers.

If you enjoy tackling technically challenging problems, and working with cutting edge technology, please apply and I would be happy to schedule a call and discuss your background and suitability for the role.

Key Responsibilities:

• You will be responsible for developing sophisticated data manipulation interfaces using TypeScript within the Microsoft Office Add-in ecosystem while also creating intuitive web applications where clients interact with their data using AI.

• You will design, build, and maintain high-performance Excel Add-ins using TypeScript and Office.js, tailored for internal Microsoft 365 deployment.

• You will develop and scale web interfaces for our AI solutions, data visualization, and reporting.
• You will work closely with our Backend team to ensure seamless integration with our cloud services while delivering exceptional user experiences in both Excel and our React-based web portal.
• You will contribute to architectural decisions, component libraries, and development best practices.

• You will support cross-team coordination around security, testing, deployment, and CI/CD pipelines.

• This role is perfect for someone who enjoys building robust user experiences that bridge traditional productivity tools (like Excel) with modern, responsive web apps; and who is excited by the opportunity to work with AI and financial data.
• This role requires deep understanding of data visualization, REST API integration, and responsive design principles.
• You will need professional frontend development experience with JavaScript, React and TypeScript.
• Strong expertise in modern UI development practices.
• Proven experience building and deploying Office Add-ins, especially within Microsoft 365 for internal enterprise use.
• Deep knowledge of the Excel JavaScript API, object models, and data handling within workbook constraints.
• Comfortable integrating with REST APIs, handling authentication flows (e.g., OAuth), and managing async data interactions.
• Strong understanding of frontend performance optimization, state management, and cross-environment compatibility.
• Experience working in Agile teams, with a proactive and ownership-driven mindset.

• Competitive salary.
• Hybrid working: we come to the office 2/3 days a week (Bank, in London / Manhattan, in New York).
• Being part of a revolutionary movement in Family Office technology.
• Working with cutting-edge AI and data technologies.
• Challenging projects that make a real impact to our sector.