Senior Developer role working with C#, .NET 4 & 6, SQL Server, Azure cloud services, SignalR, RabbitMQ, Kafka, Azure Service Bus, and CI/CD via Azure DevOps in an Agile environment. The team delivers a complex SaaS product for a regulated financial marketplace, requiring experience in financial or trading software.

Citi★3.9 (21k)· London

Work with Solidity, Web3J/Web3JS/Ethers.js/Viem, Java/Spring, Node.js, and blockchains such as Ethereum, Hyperledger Besu, Canton, and Solana, using Hardhat/Foundry/Truffle for testing. Contribute to Citi's Integrated Digital Assets Platform (CIDAP) building Web3 components for tokenization, smart contracts, and on-chain settlement.

Backend engineers use Python, Django, Django-REST-framework, GraphQL (Graphene), Celery, Postgres, and AWS (Packer, Consul, Terraform). They build and maintain the AI-driven energy management platform that powers utilities and optimises renewable generation. The global engineering team is around 1,400 people.

Python micro-services with RabbitMQ and OpenShift/Kubernetes, using SQL Server and Parquet. The London Commodities Risk Technology team builds a front-office distributed platform for trading and risk calculations on assets like oil, gas, power, and exotics, collaborating with traders and quants.

Work with C# on .Net Framework 4.5.2+ and .Net 5+, using NUnit, xUnit, REST, Kafka/RabbitMQ, Git, and Linux. You will build Citi’s next-generation Equities technology platform for execution, clearing, and margin processes.

Java (JDK 11+), multithreading, SQL/NoSQL databases (Oracle, MySQL, PostgreSQL, MongoDB, Cassandra), message queuing (Kafka, Tibco, Solace), Linux, JVM, and TDD. This tech lead role builds high-performance FX risk calculation systems for Citi’s Markets technology team, which supports global trading and risk management.

Koinly★3.0 (1)· London

Work with React 19, TypeScript, TanStack (Router, Query, Table), Radix UI, Mantine, Tailwind CSS v4, Vite, Vitest, Storybook, Highcharts, Sentry, Bun, and RabbitMQ on a data platform that reconciles crypto transactions and tax obligations for Koinly’s web application, with a React Native mobile app joining scope later.

Koinly★3.0 (1)· London

You will work with TypeScript on Bun, RabbitMQ, Redis, PostgreSQL, Vitest, Sentry, and Rust. The team owns the distributed data-processing backend that ingests, normalizes, and reconciles on-chain and exchange data for Koinly’s crypto tax calculation product.

Senior WordPress Developer role: build bespoke WordPress sites and apps using PHP, MySQL, ACF, WooCommerce, Gutenberg, JavaScript (ES6+), SASS/SCSS, Git, Composer, npm, Vite, CI/CD. You’ll also drive AI-assisted development (RAG, MCP, Copilot) and mentor junior developers.

SQL, MySQL, PostgreSQL, Doris Event, QuickSight, and possibly Amplitude, Mixpanel, GA4, Airbridge, Adjust, Airflow, dbt, Git or Python. You will own analytics schema, data models, and BI dashboards for ZYMIX, a Gen Z social super-app launching in the UK, bridging product analytics with data building.

Nuffield Health★3.2 (939)· London

You will work with Java 21, Spring Boot, Maven, RabbitMQ, Apache Camel, Git, GitHub Actions, Docker, Azure DevOps, Terraform, Ansible, and SQL databases. The Integration Squad designs, develops, and supports microservices and APIs for Nuffield Health's digital healthcare platforms, enabling secure connectivity across internal and third-party systems.

You will work with JavaScript, PHP, HTML, CSS, Laravel, Bootstrap, APIs/JSON/XML, MySQL, and optionally React. As part of a fullstack team, you will design, build, and maintain frontend and backend systems for a fine bridal jewellery manufacturer’s online platform, migrating legacy systems to Laravel.

A full-stack or backend specialist will use C# and .NET Framework, SQL Server (T-SQL), RESTful APIs, Azure DevOps, and messaging queues (RabbitMQ, Kafka) to build secure integration pipelines and backend services. They will execute a critical integration programme for an international Wealth Management firm to connect core internal and third-party systems.

Infosys★3.8 (17k)· London

You will work with Java, Spring Boot, Hibernate, JPA, React/Angular/Vue.js, HTML5, CSS3, JavaScript, RESTful APIs, SQL/NoSQL databases, Git, and CI/CD tools on cloud platforms (AWS, Azure, GCP). As a Senior Consultant at Infosys, a global digital services and consulting firm, you'll contribute across the consulting lifecycle—defining problems, proposing solutions, and guiding development, configuration, and deployment while mentoring teams and shaping client-focused solutions. Docker and Kubernetes experience is a plus.

Cato Networks seeks a Senior Full Stack Engineer for their secured access team to design and build web security solutions and internal infrastructure platforms using Java, Go, Spring Boot, GraphQL, PostgreSQL, MySQL, MongoDB, and Redis. The role involves end-to-end development from large-scale data processing to web interfaces, working on enterprise SaaS microservices at scale across security products and infrastructure. Requires 6+ years backend development experience, SaaS microservices expertise, and familiarity with relational/non-relational databases in CI/CD environments.

Work with Golang, Kubernetes, gRPC, RESTful APIs, HashiCorp Vault, and cloud-native tooling to build AI-powered platforms. The team, part of Citi's Chief Technology Office, defines the bank's tech and engineering strategy by engineering cutting-edge products at planetary scale.

As a Backend Software Engineer, you'll use Go or Node.js to build and scale the company's core real-time messaging platform, working on low-latency Pub/Sub services and state synchronization in an AI-first engineering environment.

You will work with Node.js, React, JavaScript, TypeScript, REST APIs, MySQL, Git, Next.js, Express.js, and Tailwind CSS, along with AWS or GCP cloud infrastructure. Mas & Pas Limited is the employer; no specific product or project is described in this listing.

Python (3.10+) and Go development, with JavaScript/TypeScript for frontend; using RabbitMQ, Kafka, PostgreSQL, Redis, OpenTelemetry, and Prometheus. You will build and maintain low-latency real-time data feeds and web scraping pipelines to expand access to liquidity providers for sports prediction models.

Senior Software Engineer designs and maintains backend services and APIs using Java, Python, and Node.js, working with microservices and Spring Boot. The role involves building REST, GraphQL, and SOAP APIs, using relational and NoSQL databases (MySQL, PostgreSQL, Oracle, Redis), and performing cloud-native development in AWS environments. This position supports financial systems and integrations within the leading global business aviation company, Vista.

Wise★3.5 (42)· London

Build backend

Fivetran★3.3 (8)· London

Senior Sales Engineer working with AWS, GCP, Azure, Snowflake, BigQuery, Databricks, Kubernetes, Docker, Podman, Grafana, Linux, Windows, Python, Java, and databases like Oracle, SQL Server, Postgres, MySQL, and NoSQL. The role supports Fivetran’s Commercial sales team by understanding customer data replication needs and leading proof-of-value processes for the company’s automated data pipeline and transformation solutions.

American Express★4.1 (9.7k)· London

You will work with Kotlin/JVM, Java, React, Postgres, MongoDB, Redis, Docker, Kubernetes, and GitHub Actions. The Financial Insights and Tools group builds financial analysis software for American Express customers, powered by APIs and underlying platforms for web and mobile applications.

Work with Kotlin/JVM, Java, React, APIs, Postgres, MongoDB, Redis, Docker, Kubernetes, GCP GKE, AWS ECS/EKS, Ktor, Spring, and GitHub Actions. The Financial Insights and Tools group builds customer-facing web and mobile features that aggregate and analyze financial data to enhance personal finance management.

G-Research★3.6 (18)· London

You will build automation frameworks and tooling using Python, Ansible, Terraform, and Jinja2, integrating them into CI/CD pipelines. This hands-on role sits at the intersection of networking and software engineering, developing APIs and self-service tools to power large-scale compute and research environments at a quantitative finance firm.