Top Software Engineer Jobs in London

Build production software and infrastructure for reliable, governable AI systems in customer-controlled environments. Responsibilities include developing agentic workflow components, services, APIs, evaluation pipelines, developer tools, permissions, observability, and deployment systems. The intern will debug distributed services, write maintainable code, participate in reviews, collaborate across teams, and communicate technical decisions clearly while working on a hands-on project with mentorship.

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

Develops and supports secure, scalable Java and Spring Boot applications within an agile Payments Technology team. Responsibilities include software design, production coding, troubleshooting, architecture documentation, automated testing, CI/CD, system resiliency, and high-throughput distributed systems development. The role also uses and guides responsible AI-assisted software development, analyzes application data, improves coding practices, and supports operational stability.

Build and ship production iOS features for AI-powered travel and expense experiences. Design conversational and context-aware UX, architect Swift-first applications using modern concurrency and SwiftUI, integrate networking and LLM capabilities, and support offline functionality, notifications, analytics, experimentation, and privacy. Collaborate with product, design, and backend teams while maintaining high-quality, tested code.

Build backend services and web features for Navan’s expense platform using Java, Spring Boot, TypeScript, and Python. Develop APIs, event-driven financial workflows, LLM-backed agents, document extraction, and conversational expense experiences. Improve accuracy, latency, cost, observability, and safety while maintaining idempotency, auditability, permissions, and production quality. Collaborate with Product and Design, contribute to AI evaluation, and mentor teammates.

Design, develop, test, deploy, and maintain Python applications, services, APIs, platforms, libraries, and tools supporting investment workflows including research, trading, risk management, data, and enterprise operations. Collaborate with investment professionals, quantitative researchers, and engineers; contribute to architecture and engineering best practices; and solve complex technical problems in a dynamic environment.

Build and scale backend pricing, billing, reconciliation, and automated control systems for external partners. Design secure, reliable services using Java, Kafka, MongoDB, and MariaDB, while contributing to architecture, observability, testing, incident response, and technical delivery. The role includes on-call support, mentoring, hiring participation, and cross-functional collaboration. Experience in payments, fintech, billing, regulated finance, partner integrations, compliance, reconciliation, or auditability is advantageous.

Design, build, and operate Wise’s Continuous Delivery platform using Java and Go. Extend Spinnaker, develop deployment guardrails and integrations, improve shared infrastructure, and support reliable large-scale software delivery. Responsibilities include distributed services, APIs, observability, failure handling, automation, technical design, code reviews, documentation, and collaboration with engineering teams. The role also contributes to platform operations, technical direction, and engineer development.

Build frontend-focused, full-stack features for Cisco ThousandEyes’ Endpoint platform. Develop intuitive interfaces for troubleshooting network issues and analyzing endpoint experience data, while contributing to APIs, data flows, and backend services. Collaborate with product managers, designers, and engineers to deliver reliable, accessible, high-performance solutions. Work with real-time, high-volume data streams and asynchronous events while expanding expertise in endpoint data processing and presentation.

Develop secure, scalable backend and data solutions using Java, Python, Spring Boot, Databricks, Kafka, and cloud technologies. Responsibilities include designing microservices and event-driven architectures, integrating SQL and NoSQL databases, building data workflows, writing automated tests, reviewing code, troubleshooting production systems, and improving operational stability through automation. The role also contributes to agile practices, AI-assisted development, communities of practice, and enterprise software engineering standards.

Design, provision, and operate a scalable, secure cloud data platform on AWS and Databricks using Terraform, automation (Python/Java), CI/CD, observability, and security best practices to support production analytics workloads.

Build scalable, low-latency systems for machine-to-machine payments and agentic commerce. Responsibilities include developing payment protocols, usage metering, pricing, outcome verification, authentication, billing, settlement, digital wallet integrations, and revenue attribution. The role requires secure, reliable, high-throughput software across edge infrastructure and transaction engines, collaborating with engineering, research, product, and design teams to deliver emerging commerce capabilities.

Entry-level software engineering role for new graduates joining Affirm’s Instruments team. Responsibilities include contributing to team projects, writing clear and well-tested code, navigating large codebases, debugging, participating in code reviews, collaborating with global stakeholders, communicating trade-offs, and balancing delivery speed with system quality and reliability. The role is hybrid in London during the early-career program, with future remote or office flexibility.

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.

Build and operate AI-powered developer tools, agentic workflows, backend services, APIs, and integrations with engineering platforms. The role involves applying software engineering practices to AI evaluation, testing, monitoring, and feedback loops; collaborating with developers; evolving platform architecture; and improving engineering processes and documentation.

Build scalable, performant front-end solutions using TypeScript and React across B2C and B2B products. Write testable, reliable code, contribute to technical decisions, collaborate within cross-functional squads, and drive delivery. Use authorized AI-assisted development tools for coding, testing, troubleshooting, and documentation while validating outputs for correctness, security, and performance. Share reusable engineering practices and support responsible AI adoption.

Design, develop, and launch scalable backend systems and APIs for consumer payments. Break projects into deliverable phases, collaborate with product and engineering partners, monitor system reliability, support on-call operations, review code, debug systems, and contribute to technical decisions and team development.

Build and operate scalable full-stack systems that protect customer accounts from takeovers, scams, and financial crime. Partner with Product, Design, Data Science, and Investigations teams to develop customer-facing controls, improve fraud detection, and increase automation. Responsibilities include Java and React development, distributed system design, database optimization, CI/CD, testing, independent project ownership, and mentoring junior engineers.

Build and improve data-processing infrastructure and query engines supporting Palantir Foundry. Responsibilities include optimizing query plans, developing execution capabilities, improving large-table performance, and contributing across design, coding, testing, code review, and releases. The role involves working with distributed systems, databases, compilers, operating systems, open-source technologies, and multiple programming languages while prioritizing correctness, compatibility, and performance.

Work on query engines and data-processing infrastructure supporting Palantir Foundry. Responsibilities include optimizing query plans, developing execution-engine capabilities, improving large-table performance, and delivering production code through design, review, testing, and release. The role involves Java, Scala, Rust, Python, open-source systems, databases, compilers, operating systems, and distributed systems while emphasizing correctness, compatibility, and measurable performance.

Build and maintain DevSecOps tooling for AWS cloud environments, including threat modeling, security guardrails, policy-as-code, vulnerability analysis, compliance reporting, and runtime security visibility. Develop automation for security findings and software supply chain controls, support audits and incident response, and provide remediation guidance to engineering teams. Collaborate with platform engineers, product squads, risk, and governance teams while using authorized AI-assisted development tools securely and validating generated outputs.

Design, develop, and deliver frontend (React) and backend services; produce architecture artifacts; analyze large data sets and visualizations; improve code quality and system resiliency; mentor junior engineers; use enterprise-authorized AI-assisted development tools; contribute to engineering communities and continuous improvement of infrastructure platform services.

Designs, develops, tests, troubleshoots, and maintains secure, scalable software solutions within an agile Market Risk Technology team. Produces architecture and design artifacts, develops production code, analyzes large datasets, and improves system architecture, coding practices, resiliency, and automation. Uses enterprise-authorized AI-assisted development tools responsibly while validating generated code for correctness, performance, and security. Preferred experience includes Python, AWS, and data engineering.

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.

Lead the architecture, development, governance, and operational support of a Salesforce CRM servicing platform. Translate business needs into scalable technical solutions, oversee integrated Salesforce implementations, establish architecture standards, manage risks, and champion security, testing, CI/CD, observability, and operational resilience. Partner across engineering teams in a Kafka-based event-driven microservices environment while mentoring engineers and driving technical alignment.