Top Software Engineer Jobs in London

Develop and operate highly available, scalable, low-latency Java components for a global macro e-trading platform. Responsibilities include system design, software development, testing, deployment, performance optimization, troubleshooting, and operational support. The role requires expertise in Linux/Unix, networking, middleware, FIX protocol, CI/CD, automated testing, secure software development, and responsible use of AI-assisted engineering tools. Collaboration with global developers and trading partners is central, with relevant FX or Rates e-trading experience preferred.

As a Software Engineer at Citadel, you will build systems for investments, collaborate with researchers, and tackle complex problems.

11-week internship building high-performance research platforms and trading tools. Work in small teams on distributed systems, NLP/ML applications, and web frameworks while collaborating with senior engineers.

Develop features and game functionality for an unannounced mobile free-to-play action game using Unreal Engine 5. Work across gameplay, meta systems, and core technology; build tools for engineers and content creators; scope tasks and systems; and triage bugs. Collaborate with design and backend teams in a hybrid London-based environment.

Build high-performance tools and large-data research platforms to enable trading strategies. Work in small engineering teams to design systems, develop platforms and web frameworks, and apply techniques such as distributed computing, NLP, and machine learning to solve complex problems.

Build and operate high-scale platform infrastructure, including Redis/Valkey, Memcached, Elasticsearch, Kubernetes, and observability systems. Develop operators, automation, CLIs, and self-service tooling; lead capacity planning, migrations, and upgrades; improve reliability, performance, and cost efficiency; investigate production incidents; support on-call operations; and collaborate with engineering teams on system usage, monitoring, and performance.

Build scalable software for agent-web interactions, including edge services, data pipelines, protocol integrations, developer tools, content controls, and analytics. Develop support for MCP and related emerging standards, ensuring secure, reliable, high-performance systems. Collaborate with engineering, research, product, design, and other stakeholders to take concepts into production while evaluating AI-agent interactions with websites and applications.

Build, deploy, and maintain full-stack AI applications, services, and data pipelines for enterprise use. Collaborate with data scientists, machine learning engineers, research scientists, and technical teams to productionize AI products. Develop secure, scalable, resilient software; maintain APIs and backend services; conduct code reviews; troubleshoot complex issues; apply CI/CD and software security practices; and support LLM applications using retrieval-augmented generation and prompt design.

Software Engineering Interns will ship projects affecting Cloudflare’s global Internet network, collaborate cross-functionally, work with mentors, and present their completed projects. Interns will develop software at Internet scale using technologies such as TypeScript, JavaScript, Go, Rust, C/C++, and Python. The role requires a full-time, 12-week minimum commitment in Cloudflare’s London office three to five days per week.

Leads software architecture and engineering excellence for enterprise-scale infrastructure features. Builds and evolves full-stack, user-facing web products with a backend focus, working across UI, databases, data governance, and account controls. Partners with Product and Design from conception through deployment, contributes hands-on code, and provides technical leadership without people management responsibilities.

Design, develop, test, and maintain Java and Kotlin backend services, REST APIs, payment orchestration systems, and event-driven financial platforms. Build scalable services on AWS, optimize PostgreSQL databases and SQL queries, and support card pay-in functionality. Collaborate cross-functionally, conduct code reviews, resolve performance issues, participate in on-call rotations, and ensure secure handling of financial data.

Design, develop, test, and support secure, scalable, low-latency electronic trading software using Java and Spring. Contribute to architecture, system integrations, performance optimization, production support, incident resolution, automated testing, CI/CD, observability, code reviews, and continuous engineering improvements. Apply FIX protocol expertise while collaborating within an agile team.

Designs and develops secure, scalable agentic commerce solutions for payments. Responsibilities include building agent orchestration components and MCP servers, developing Python services, creating Databricks data pipelines, supporting MLOps workflows, evaluating agent behavior, implementing observability, and improving operational stability. The role requires cloud-native engineering, API and event-driven services, LLM application development, responsible AI practices, Kubernetes, and secure production software delivery.

Build and maintain full-stack SaaS features across backend and frontend: develop scalable Python and .NET services, create React/TypeScript UIs, design and integrate REST/gRPC APIs, support cloud-native deployments, production monitoring, incident resolution, and apply security, CI/CD, and testing best practices while collaborating with product and business stakeholders.

Build and scale full-stack services supporting international SMS expansion and RCS capabilities. Design new services, work across monolithic and microservices architectures, optimize databases and application performance, develop CI/CD pipelines, debug production issues, and collaborate across teams. The role involves Python, Django, Go, React, AWS, distributed systems, and modern DevOps tooling, with a focus on reliable mobile messaging products for global customers.

Build and operate scalable full-stack systems that prevent fraud, account takeovers, scams, and financial crime. Own projects end to end, develop customer-facing security controls, improve transaction monitoring and detection capabilities, and collaborate with Product, Design, Data Science, and Investigations. The role requires Java or JVM expertise, Spring, modern frontend development, distributed systems, databases, CI/CD, testing, strong product judgment, and mentoring junior engineers.

Build full-stack AI-enabled applications and backend services integrating MCP servers, LLMs, RAG retrieval, and agent orchestration. Design reusable MCP tools/skills, implement secure RBAC, ensure observability, and prepare deployments for OpenShift/Kubernetes while collaborating across product and platform teams.

Design, build, run, and scale distributed tools and data pipelines to support threat disruption and platform abuse efforts. Translate legal and security requirements into scalable services, improve system architecture, monitor production (on-call), collaborate with Threat Intelligence, Legal and Product teams, and mentor other developers to promote testing and best practices.

Design, develop, and maintain secure, scalable software solutions as a seasoned agile team member. Produce high-quality production code, architecture/design artifacts, data visualizations, and troubleshooting. Use CI/CD, resilient application patterns, enterprise AI-assisted development tools, and validate AI outputs. Contribute to engineering communities and improve code hygiene and system architecture.

Software engineering intern supporting the Platform Engines group and Policy Engine for SailPoint’s cloud identity security platform. Responsibilities include developing software, procedures, and test solutions; collaborating with software and QA engineers, technical writers, and product managers; and working in Agile teams. The intern will gain exposure to cloud and software technologies including Golang, Angular, AWS, Docker, Kafka, Kubernetes, REST, SQL, and Temporal.

Develop and deliver production AI/ML solutions across the full lifecycle using Agile methodologies. Translate business requirements into technical specifications, build secure production code and algorithms, create architecture artifacts, analyze large datasets, develop visualizations, troubleshoot systems, and identify improvements. The role requires expertise in machine learning, Python, Spark, distributed computing, AI frameworks, agentic workflows, and AWS services, while contributing to engineering communities and emerging technology initiatives.

Design, develop, troubleshoot, and maintain scalable software solutions on a Kafka platform team. Build secure Java-based Kafka consumers and producers, administer event-streaming systems, and support AWS and Kubernetes deployments. Create architecture artifacts, analyze large datasets, improve system reliability and coding practices, and use AI-assisted development tools responsibly within secure software delivery workflows.

Build and deploy customer-focused Android applications for Wise Assets. Develop maintainable, testable Kotlin code using modern architectures, structured concurrency, dependency injection, and REST APIs. Collaborate cross-functionally, prioritize user needs through data-driven decisions, communicate technical concepts clearly, and proactively solve problems. Familiarity with Jetpack Compose, Gradle, and GitHub Actions is advantageous.

Design and build query planning, optimization, execution, storage, and incremental processing capabilities for Palantir Foundry. Extend distributed data engines and Iceberg integrations, improve correctness and performance, investigate complex system issues, and develop tests and benchmarks. Collaborate with product teams, customers, and open-source communities to deliver reliable data infrastructure.

Build and scale backend systems for Wise’s Product Eligibility platform, determining which products and features are available to customers. Responsibilities include shaping technical vision, developing distributed systems, designing APIs and database schemas, optimizing queries, supporting platform and back-office tooling, contributing to customer-facing flows, and collaborating in an agile team with product and analytics partners.