Senior Full Stack (Java/Kotlin/React/TS) Engineer

JUXT; Greater London; On-site; GBP 100,000 - 150,000; Full time

Job summary

JUXT is seeking a Senior Full Stack Engineer to join a Tier 1 investment bank transformation. You will build Java/Kotlin event-driven services and React/TypeScript applications that power live, financially critical systems.

You’ll modernise legacy trading and post-trade platforms, design for failure, data integrity and replay, and work across Kafka, Kubernetes, CI/CD and cloud-native stacks. Strong architectural instincts and senior autonomy are expected.

Qualifications

• Experience building Java/Kotlin event-driven services in production environments.
• Strong React/TypeScript UI development experience.
• Hands-on with Kafka-based messaging and data streaming.
• Cloud-native architectures using Docker/Kubernetes and CI/CD pipelines.
• Proficient in TDD and automated test strategies.
• Background in capital markets, trading or post-trade systems.

Responsibilities

• Build Java/Kotlin event-driven services and modern React/TypeScript applications.
• Modernise legacy trading and post-trade systems.
• Design for failure handling, ordering, replay and data integrity.
• Apply TDD across unit, integration and E2E tests.
• Work with Kafka, Solace, TIBCO EMS, SQL Server, MongoDB.
• Build and deploy using Docker, Kubernetes/OpenShift & CI/CD.
• Leverage OpenTelemetry, ELK and Grafana for observability.
• Explore AI-assisted coding tools for legacy analysis and refactoring.
• Demonstrate senior autonomy with strong architectural instincts.

Skills

Java/Kotlin event-driven

React/TypeScript

Kafka

SQL Server

MongoDB

Docker

Kubernetes/OpenShift

CI/CD

TDD

OpenTelemetry

ELK

Grafana

Redux

WebSockets

API integration

Capital markets

Event-sourcing

Trunk-based development

Job description

Senior Full Stack Engineer - Java/Kotlin&React

We are partnering with a Tier 1 investment bank on a major, multi-year transformation of its Prime Finance Equities platform.

The Equity Accelerator programme is re-engineering core trading and post-trade systems, replacing legacy architecture with modern event-driven, cloud-native technology and delivering advanced capabilities includingcross-margining and credit financing.

This is a genuine engineering role working on live, financially critical systems - not a greenfield project or generic Java delivery.

What you'll be doing

• Build Java/Kotlin event-driven services and modern React/TypeScript applications
• Modernise complex legacy trading and post-trade systems
• Design for failure handling, ordering, replay and data integrity
• Apply TDD across unit, integration and E2E testing
• Work with Kafka, Solace, TIBCO EMS, SQL Server&MongoDB
• Build and deploy using Docker, Kubernetes/OpenShift&CI/CD
• Work with OpenTelemetry, ELK&Grafana
• Use AI-assisted/agentic coding toolsfor legacy analysis, testing and refactoring
• Kotlin experience or willingness to learn
• Event-driven / message-passing / event-sourcing experience
• Redux, WebSockets and API integration
• Genuine hands-on TDD experience
• Background in capital markets, trading or post-trade
• Experience with iterative delivery, trunk-based development and CI/CD
• Senior-level autonomy and strong architectural instincts

Prime Brokerage, Synthetic/Swap or Cash Equities experience, plus exposure to Corporate Actions, 871(m), EMIR, MiFID, Kafka, SQL Server, Kubernetes/OpenShift or cloud-native platforms.

If you're a senior full-stack engineer looking to work on complex financial technology with real business impact, I'd be keen to speak.

*We cannot offer sponsorship for this role*