Senior / Principal Frontend Engineer – Smart Software Rewrite Platform

JUXT (part of of Grid Dynamics) is partnering with a Tier 1 investment bank to build a platform that automates large-scale software migration and code modernisation.

The platform will enable engineering teams to evolve existing systems rapidly and safely, automating complex code transformations such as major framework upgrades, technology migrations and security improvements.

As a Frontend Engineer, you will be responsible for building the user-facing experience of this platform. You'll work primarily with React and TypeScript, creating an intuitive self-service application through which engineering teams can:

• Enrol and manage software repositories
• Configure and initiate migration or refactoring jobs
• Monitor jobs and their progress
• Review transformation results
• Investigate errors and issues
• Understand the changes made to their codebases
• Work efficiently through large-scale software modernisation workflows

You'll work closely with backend engineers, platform engineers and the users of the system to shape both the product and its technical implementation.

We're looking for a Frontend Engineer who enjoys building high-quality software and is comfortable working on technically complex products.

You will have significant influence over the frontend architecture, user experience and development practices of the platform.

The role combines hands-on engineering with close collaboration across disciplines. You'll be expected to understand the problems users are trying to solve, work pragmatically with the backend team, and build a frontend that makes sophisticated technical workflows straightforward for its users.

Essential functions

Key Responsibilities

Frontend Development

• Design, build and maintain the platform's self-service frontend using React and TypeScript.
• Develop reusable, maintainable and well-tested UI components.
• Build intuitive workflows for repository enrolment, job configuration, execution and review.
• Implement complex data-driven interfaces while keeping the user experience clear and responsive.
• Manage frontend application state and asynchronous workflows effectively.
• Ensure the application remains maintainable as the platform and number of users grow.
• Contribute to frontend architecture and technical decisions.

API Integration

• Integrate the frontend with Java/Spring REST APIs.
• Work closely with backend engineers to design and evolve API contracts.
• Handle loading, error, retry and empty states appropriately.
• Model and consume complex API data using TypeScript.
• Help identify opportunities to improve API design from a frontend consumer's perspective.

Authentication & Authorisation

• Integrate the application with OpenID Connect (OIDC).
• Work with authentication and authorisation flows appropriate for an enterprise banking environment.
• Implement secure handling of authenticated user sessions and access control.
• Collaborate with platform and security engineers to ensure appropriate security practices are followed.

Product & User Collaboration

• Work directly with engineering teams using the platform to understand their workflows and pain points.
• Iterate on the product based on user feedback.
• Translate complex technical workflows into simple, effective user experiences.
• Collaborate with designers, backend engineers and other stakeholders where appropriate.
• Balance user experience, technical quality and delivery pragmatism.

Engineering Practices

• Write clean, readable and maintainable TypeScript.
• Build automated tests for frontend functionality.
• Participate in code reviews and technical discussions.
• Contribute to engineering standards and development practices.
• Identify technical risks and propose practical solutions.
• Help continuously improve the team's development workflow and engineering quality.

Frontend

• JavaScript
• TypeScript
• React

Authentication

• OpenID Connect (OIDC)

Backend Integration

• Java
• Spring
• REST APIs

The role is primarily frontend-focused, but you'll work closely with the backend and platform teams and should be comfortable understanding how distributed systems and APIs fit together.

Qualifications

We're looking for strong frontend engineering experience, particularly with modern JavaScript and React applications.

You should have:

• Strong commercial experience building applications with React.
• Strong knowledge of TypeScript and modern JavaScript.
• Experience building production-quality web applications.
• Experience integrating frontend applications with REST APIs.
• Understanding of asynchronous application behaviour and API-driven workflows.
• Experience with authentication and authorisation concepts.
• Familiarity with OpenID Connect, OAuth 2.0 or similar identity protocols.
• Experience writing automated frontend tests.
• Good understanding of frontend architecture and component design.
• Strong Git-based development practices.
• Experience collaborating closely with backend engineers and other technical stakeholders.

Would be a plus

Experience in any of the following would be beneficial:

• Enterprise or financial-services software development.
• Developer tooling or internal engineering platforms.
• Large-scale software modernisation or migration.
• Code transformation or refactoring tooling.
• Java/Spring backend environments.
• OpenID Connect implementations.
• OAuth 2.0 and enterprise identity platforms.
• Complex asynchronous workflows.
• Data-intensive user interfaces.
• Design systems and reusable component libraries.
• CI/CD and modern software delivery practices.
• Cloud-based application development.
• Working within highly regulated or security-conscious environments.

Beyond technical skills, we're looking for engineers who fit the way JUXT (part of Grid Dynamics) works.

You are likely to thrive in this role if you are:

Pragmatic

You care about solving the right problem rather than following process for its own sake. You understand trade-offs and make sensible engineering decisions.

Collaborative

You enjoy working with other engineers and users, sharing ideas, challenging assumptions constructively and helping the team arrive at good solutions.

Perceptive

You can understand both the technical problem and the underlying user need. You pay attention to the details that make software genuinely useful.

Independent

You are comfortable taking ownership of problems and making decisions without needing everything prescribed in advance.

Quality-focused

You care about producing software that is understandable, maintainable, secure and reliable.

Human

You communicate clearly, treat colleagues with respect and appreciate that good engineering is ultimately about helping people solve problems.

You'll be embedded within a team delivering a significant engineering platform for a Tier 1 investment bank.

The environment is technically demanding, with opportunities to work on problems involving:

• Large-scale software migration
• Enterprise application architecture
• Developer productivity
• Secure software delivery
• Authentication and authorisation
• Distributed systems
• Complex API-driven workflows
• Modern frontend engineering

You'll work alongside experienced engineers and have the opportunity to influence both the technical direction of the frontend and the way users interact with the platform.

Location: London

Working model: Hybrid, with 3 days per week in the office.

The role involves close collaboration with engineers and users, so regular in-person interaction is an important part of the engagement.

We are open to considering both:

• Permanent employment
• Contract engagements

The exact arrangements, duration and commercial terms will depend on the engagement.

This is an opportunity to work on a technically ambitious product at the intersection of:

Frontend engineering + developer tooling + software modernisation + financial services.

Rather than building a conventional business application, you'll be creating the interface through which engineering teams manage sophisticated automated code transformations across large software estates.

You'll have the opportunity to work with modern frontend technologies, solve genuinely challenging engineering problems, collaborate directly with experienced engineers and contribute to a platform designed to materially improve how large organisations modernise software.

Required / primary:

• React
• TypeScript
• JavaScript
• REST APIs
• OpenID Connect

Working alongside:

• Java
• Spring
• Enterprise authentication and authorisation systems

We are looking for a Frontend Engineer to join a team building a smart software rewrite and migration platform for a Tier 1 investment bank.

You'll own significant parts of the React/TypeScript frontend, integrating it with Java/Spring APIs and enterprise authentication systems while working closely with the engineers who will use the platform.

The ideal candidate is a strong frontend engineer who combines technical depth with pragmatic decision-making, good communication and a genuine interest in building software that makes complex engineering work simpler.

We offer

• Opportunity to work on bleeding-edge projects
• Work with a highly motivated and dedicated team
• Competitive salary
• Flexible schedule
• Benefits package - medical insurance, sports
• Corporate social events
• Professional development opportunities
• Well-equipped office

About us

Grid Dynamics (NASDAQ: GDYN) is a leading provider of technology consulting, platform and product engineering, AI, and advanced analytics services. Fusing technical vision with business acumen, we solve the most pressing technical challenges and enable positive business outcomes for enterprise companies undergoing business transformation. A key differentiator for Grid Dynamics is our 8 years of experience and leadership in enterprise AI, supported by profound expertise and ongoing investment in data, analytics, cloud & DevOps, application modernization and customer experience. Founded in 2006, Grid Dynamics is headquartered in Silicon Valley with offices across the Americas, Europe, and India.