A Senior Full Stack Developer is needed to work with Angular, .NET, and legacy ASP.NET MVC. The role involves developing, enhancing, and modernising business-critical Front Office applications for an Investment Bank.

Teksystems★3.8 (4.7k)· London

You will work with Java (Spring Boot) and Angular to enhance and maintain a large-scale customer relationship management platform for a Tier 1 banking client.

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 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'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.

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.

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.

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.

Amazon★3.5 (56k)· London

This role involves designing and building scalable security systems, with development in Java, C++, or C#. You’ll automate pentest processes and create a greenfield product that provides critical security details about Amazon applications, working with teams across the company. The position involves owning architecture, design, and reliability for new and existing systems.

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.

Proton★5.0 (1)· London

You will work with .NET, Windows desktop application development, multi-threaded programming, file systems, Git, GitLab CI/CD, and monitoring/alerting frameworks. You’ll build and maintain Proton Drive for Windows, a privacy-by-default application that manages local and remote state and performs cryptographic operations.

You’ll use Claude Code, Figma, LinkedIn, Google PPC, Reddit, Meta, and SEO/AEO/GEO to build campaigns, landing pages, and assets. AirSpeed’s AI Revenue Orchestration Platform turns customer interactions into insight and action. This is the first dedicated demand-generation and digital-presence role, operating as a hands-on individual contributor with no team to start.

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.

Blockchain★3.4 (14)· London

Lead a small engineering team building crypto savings and crypto-backed lending products at Blockchain, using Kotlin or Java, Kafka, PostgreSQL, and Redis. You will define technical architecture, design distributed systems, and drive best practices in a hands-on role.

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.

You’ll build server-side game logic on a Java code base implementing slot mechanics, reel logic, and bonus flows. Working closely with Game Mathematicians, you’ll own a game from concept through to release, handling configuration, metadata, and client integration. You’ll also refactor and modernise the platform, using Git and working in an Agile Scrum environment.

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.

Alto★2.7 (212)· London

Fullstack engineer role working with TypeScript, Node.js, C#, .NET, React frontend, and AWS services (ECS/Fargate, Lambda, SQS, DynamoDB, DocumentDB), plus Terraform, SST, and AI coding agents like Claude Code and Cursor. You'll build microfrontend web apps and evolve event-driven architecture for Alto Software Group, a B2B SaaS platform powering UK housing transactions. This is a 12-month maternity cover position.

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.