Full Stack Developer role using C#, .NET, JavaScript, and Umbraco for an established luxury travel company. The work involves a major transformation programme building web-based tools to automate operational tasks, improve pricing accuracy and management information, plus website enhancements.

You'll work with Kubernetes, Terraform, Python, AWS or GCP, and CI/CD tools (GitHub Actions, GitLab CI, Argo CD), plus observability stacks (Datadog, Prometheus, Grafana). You'll bring SRE discipline to an AI platform hosting model serving, agent orchestration, and batch inference.

Build, run, and evolve the API gateway and routing layer connecting engineers and client workloads to multiple LLM providers (Anthropic, AWS Bedrock, OpenAI), including failover and routing strategies, using Python or Go. The team also designs orchestration and lifecycle management for AI capabilities and implements RBAC/OIDC access controls. This is a role within CreateFuture, an AI-native consulting partner building digital products for clients.

Build and run the API gateway and routing layer connecting workloads to Anthropic, AWS Bedrock, and OpenAI using Python or Go, Kong or Envoy, and RBAC/OIDC. The team creates the infrastructure and orchestration tooling that turns AI integrations into a reusable "capability marketplace" with governance controls. Senior engineers own delivery of key platform components from the gateway through orchestration.

You will build evaluation, experimentation, and observability pipelines using Python and platforms like Braintrust, LangSmith, Arize, and Weights & Biases, plus design LLM-as-judge and human-in-the-loop scoring. The role focuses on AI-native consulting for clients like PayPal and adidas, including production monitoring, quality signal detection, and cost attribution. You'll also wire evaluation gates into CI/CD pipelines for the AI Engineering team.

You will work with Python or Go, API gateways (Kong, Envoy, or Apigee), multiple LLM providers (Anthropic, AWS Bedrock, OpenAI), RBAC/OIDC, and MCP or service-registry patterns. As part of the AI Platform Engineering team, you will build and run the infrastructure—API gateway, orchestration tooling, and governance controls—that connects engineers and client workloads to LLM providers. In this Principal role, you set technical direction for the platform and act as a trusted extension of CreateFuture’s leadership.

Lead Software Engineers use TypeScript, Java, Golang, Rust, Python; deploy on Kubernetes and Google Cloud; and work with BigQuery, REST, and observability tools. They build and scale supplier integration, search/recommendation, real-time pricing, ML marketing, booking/payment/fulfillment, and AI-powered systems for the company’s packaged-holiday platform.

Thomson Reuters★3.9 (4.3k)· London

Work with Java and Python across containerized services, relational databases, and distributed systems, including AI/LLM integration patterns. As a Principal Engineer on Thomson Reuters' HighQ, an enterprise collaboration platform for law firms, you will set technical direction, architect scalable systems, and lead the integration of AI and agent platforms.

Build REST and GraphQL APIs and MCP servers in Python (FastAPI, Flask) to expose ML models from Databricks to internal apps, CRM platforms, and AI agents at RBC. Work within the Data Science team to architect the serving layer, handling contract design, authentication, and documentation.

You'll work with JavaScript, Node.js, Express, React, and MongoDB/Mongoose to set technical direction and oversee AI-assisted content-creation features. As Fractional Head of Product at StoryTerrace, you'll own the roadmap for two B2C platforms—an established product and a new self-serve app—directing one Full Stack Developer and advising on hiring. This role reports to the CEO and requires hands-on coding experience to unblock development.

JELLYFISH★3.5 (32)· London

The role focuses on building and extending an agentic delivery stack using tool APIs, MCP servers, AI harnesses, agentic operating systems, and Python. You will drive agentic delivery and adoption both inside Jellyfish, a global digital marketing agency, and with its enterprise clients. This is a 4-month fixed-term contract.

Relay Technologies★2.0 (9)· London

At Relay Technologies you will build and own time-series forecasting models for parcel volume, inbound international volume, and parcel size/weight, using Python and ML frameworks. You will work on the Network squad’s demand-forecasting engine that predicts parcel movement across sortation, middle-mile, and last-mile operations, directly affecting cost per parcel. This is a hands-on individual-contributor role, serving as the technical anchor for Demand Forecasting, collaborating with a Senior Data Scientist, ML Engineer, and Analyst.

Cognizant★3.8 (17k)· London

You will work with Python (FastAPI or Flask) in a serverless architecture, integrating with a NextJS/React frontend and third-party APIs. You will help build and enhance the NHS Digital Onboarding Service (DOS) for the NHS API Platform.

Meta★4.0 (1.1k)· London

Work with languages such as C++, Java, Swift, Kotlin, Python, JavaScript, and Hack to build and optimize user-facing applications across mobile and web. As a member of Meta’s product engineering teams, you’ll help advance its platforms—Facebook, Instagram, WhatsApp, and immersive AR/VR experiences—that connect billions globally.

Google★4.3 (6.2k)· London

Work with C++, Python, or Rust to build the Google Cloud Universal Ledger (GCUL), a payments platform addressing cost, speed, and fragmentation. Implement critical ledger capabilities including consensus, transaction dissemination, and data privacy via homomorphic cryptography and zero-knowledge proofs.

Sainsbury’s★3.5 (16k)· London

You will build and integrate server‑side logic for the Multichannel Messaging Hub, using Node.js, TypeScript, microservices, REST/JSON/SOAP APIs, Kafka, Snowflake, AWS serverless services, Kubernetes, and Terraform. The team of 7 engineers owns cross‑channel campaign delivery for Sainsbury’s brands.

Standard Chartered★4.1 (3.3k)· London

Senior developer role on Standard Chartered’s Blade platform (in-house pricing, execution, and trade processing) using JavaScript, TypeScript, React, Redux, RxJS, Webpack, CSS, HTML, Azure DevOps CI/CD, and preferably Java backend.

You'll work with Python, React, TypeScript, and AI coding agents across the full stack. TreasurySpring is a London fintech building a regulated Fixed-Term Fund platform that replaces manual institutional treasury processes and legacy systems with digital cash-management products for investors and corporations.

You'll work with TypeScript/Node.js, React, Java/Kotlin, REST APIs, event-driven architectures, AWS, Docker, Kubernetes, Kafka, Keycloak, and observability tooling. You'll lead the PRIIP Cloud platform, WallStreetdocs' cloud-based documentation and reporting system for structured products and derivatives in regulated financial services. No team size is specified.

Tesco★3.5 (25k)· London

You will work with Java, Spring Boot, Kafka, Apache Flink, Apache Beam, NoSQL databases, Redis, and Apache Camel. The Tesco Personalisation team builds real-time, low-latency services for recommendations, offers, and experimentation across web, mobile, and in-store channels using streaming data and ML.

You will build and maintain server-side applications and APIs using Node.js, Python, Java, C#, PHP, and Ruby on Rails, working with MySQL, PostgreSQL, MongoDB, and cloud platforms AWS and Azure. You will join the development team to design scalable backend systems for the company’s web platforms, collaborating with front-end developers using Angular and React.

Build responsive React/TypeScript interfaces with Next.js, Vite, pnpm, Chakra UI, and Storybook; integrate blockchain interactions using wagmi/viem while managing state with TanStack Query and Zustand. You'll develop the frontend for Symbiotic’s onchain collateral infrastructure, powering vaults, stakers, and operators in neofinance applications.

Citi★3.9 (21k)· London

You will work with TypeScript, React, HTML5, CSS, JavaScript (ES6+), Chromium/Electron/OpenFin, FDC3, REST/WebSocket APIs, Kafka/Solace/Tibco, and CI/CD with Jenkins. The team delivers pricing solutions and trading GUIs for Citi’s Foreign Exchange business. You will provide technical leadership, mentor junior engineers, and drive AI integration.

Senior Research Engineer at Decagon will work with Python, modern ML tooling, and LLM post-training and deployment to build conversational AI models powering the company's enterprise support agents. You'll own multi-quarter initiatives improving model reliability, capability, and efficiency through research in instruction following, retrieval, memory, and task completion, taking projects from prototype to production. The role requires 5+ years in AI/ML engineering with proven production LLM deployment experience.

You'll build the UI/UX for AI-powered intellectual property tools using TypeScript, React, and full-stack frameworks, with Python backend and WYSIWYG editors (TinyMCE/CKEditor) for patent attorney workflows. Solve Intelligence provides AI infrastructure for the IP industry, serving 600+ global teams including DLA Piper with 20-30% monthly revenue growth. As a founding engineer on a small, talent-dense team, you'll own product evolution and end-to-end feature delivery across the stack.