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.

Principal C#/.NET engineer leading solution design and hands-on development using C#, .NET Core, MongoDB, SQL Server, Kafka/ActiveMQ, and OpenShift/Kubernetes. Mentors developers and directs engineering, applying SOLID, microservices, and contract-first API design within a regulated financial services environment.

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.

You will work with Python, JavaScript, SQL, Kafka, AWS/Azure, PostgreSQL, SQL Server, ClickHouse, and MongoDB. The team designs and delivers real-time, high-performance trading systems for Energy & Commodities, integrating market data, risk, and front-to-back office workflows.

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.

Work with Microsoft Azure data platforms: Azure Synapse, Azure SQL Server, Azure Data Factory, Azure DevOps, Microsoft Fabric, and OneLake; also uses DBT and Spark. You will modernize core data platforms—ingesting data from MS Dynamics CRM, Finance & Operations, and SAP SuccessFactors—to power analytics, AI-driven insights, and executive decision-making.

SmartestEnergy★4.1 (15)· London

You will work with Microsoft Azure Data Platform, Microsoft Fabric, PySpark, SQL, Python, Azure DevOps, CI/CD, and Power BI to build enterprise-scale data pipelines and Data Lakehouse/Data Warehouse solutions. The team develops modern cloud-based data solutions supporting ETL/ELT processes across Medallion Architecture for SmartestEnergy’s energy digitisation and decarbonisation goals.

HSBC★4.0 (16k)· London

Work with Python, Docker, Kubernetes, Flask/FastAPI, PyTorch/TensorFlow, SQL Server/Postgres, and CI/CD pipelines to build and deploy production-grade ML and GenAI services. You will join the Growth AI programme within HSBC’s Corporate & Institutional Banking Data & Analytics, developing AI applications to identify business opportunities and mitigate client attrition.

You will build and maintain Python services using FastAPI and Azure Functions, design and consume REST APIs, work with MS SQL Server, and leverage Azure infrastructure. The team delivers a loan management platform for a global financial services firm, handling complex servicing workflows in a regulated environment.

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.

Work with Azure and AWS cloud platforms, programming in Java and Python, and big data frameworks including Hadoop, Spark, Apache Hive alongside Informatica and SQL databases (Microsoft SQL Server, Oracle). The role involves data processing tasks within Assura Protect's cloud infrastructure.

NHS★3.6 (9.8k)· London

Work with SQL Server, Qlikview, Qlik Sense, SSIS, and SSRS for configuration, backup, performance tuning, and administration. You will develop and enhance a reporting environment that integrates data from clinical systems, supporting London North West University Healthcare Trust and Hillingdon Hospitals NHS Foundation Trust.

Works with .NET, C#, Azure (Functions, Service Bus, Cosmos DB), SQL Server, and explores AI concepts (LLMs, prompt engineering). The engineering team builds publishing systems for content delivery, access control, workflow, analytics, and eCommerce at Sage, an academic publisher. The leadership role shapes technical direction and mentors colleagues.

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'll work with Blazor, Razor pages, MVC, C# .NET, ASP.NET Core APIs, MS SQL Server, Azure data technologies and Azure DevOps. The Analytics Product Engineering team builds and manages a bespoke analytical platform for insurance pricing, exposure management, event response and underwriting tools.

Mott MacDonald★3.9 (699)· London

Design, build and maintain a scalable internal developer platform using Terraform, Kubernetes, Docker, and GitHub Actions, with cloud platforms (ideally Azure) and observability tools like Prometheus, Grafana, or ELK. You will work within Mott MacDonald’s Digital Unit to provide platform solutions that help clients derive value from information, supported by a global team.

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.

Work with SQL Server, QlikView, Qlik Sense, SSIS, and SSRS to administer and enhance a reporting environment. You will support two NHS trusts by integrating data from a wide range of clinical systems to improve service delivery.

Lead the Credit Risk Analytics IT team using S&P Global FRA (fraimWRX), Redis, Kafka, Spark, HBASE, HDFS, Kubernetes, Python, .NET, C#, MS SQL Server, and MS Azure. The team designs, integrates, and supports systems for calculating and reporting Credit Risk across all locations. This is a VP-level role managing onshore, nearshore, and offshore developers.

You will build and maintain publishing systems using .NET, C#, Azure (Functions, Service Bus, Cosmos DB, Key Vault), and SQL Server, with opportunities to explore AI‑enabled development. Your team handles content delivery, access control, workflow, analytics, eCommerce, finance, and metadata management for a global academic publisher.

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 C#, the latest .NET platform, and SQL Server, Oracle, or equivalent relational databases. The role is being recruited by Spectrum IT Recruitment, a tech recruitment firm.

Work with F#, C#, Python, Kubernetes, PostgreSQL and React to build platforms and tooling that power large-scale research workloads. You will develop frameworks and services enabling researchers to run millions of computations across a globally distributed compute estate.

Expedia Group★3.8 (1.2k)· London

Backend role building pricing services for Expedia Group's travel platform using Java, Scala, Kotlin, Spring, MSSQL, DynamoDB, Redis. You'll design and maintain high-throughput, low-latency distributed microservices and caching mechanisms.