26 to 50 of 116 API Design Jobs in London

first‐class concerns. Inputting into architecture and technical direction in collaboration with Principal Engineers – making considered, well‐reasoned decisions on service boundaries, data design, messaging patterns, consistency guarantees and performance. Championing a high‐quality engineering culture – test coverage, peer review, CI/CD discipline via GitHub Actions, Infrastructure … proven senior-to-staff-level backend engineer with deep, current expertise in C# and .NET Core 8/9 – you can architect and lead design of distributed REST API microservices at scale. Authority in AWS serverless architecture – Lambda‐first, with strong working knowledge of API Gateway ...

Python (pyspark): Experience with data pipelines and analytics is a plus. Power BI: Familiarity with developing dashboards and data models. Architecture: Knowledge of microservices, API design, and event-driven architectures. DevOps/CI/CD: Experience with Azure DevOps, GitLab, GitHub Actions, or similar tools. Cloud Platforms: Proficient … Azure or AWS (Azure preferred). Databases: Strong skills in SQL Server, PostgreSQL, or other relational databases. Key Responsibilities Design & Develop: Create and maintain full stack applications using React JS and C#.NET Core. Build Services: Develop high-performance backend services and RESTful APIs with a focus on scalability ...

solutions and enabling tangible value through technology. This role is a full-stack engineering role (covering frontend, backend, data, infrastructure) and collaborates on solution design, implementation, deployment, testing and support.**Responsibilities:*** Design, build, and improve modern application services that support a strategic business platform, with a focus … strong track record of delivering production systems.* Strong experience building backend applications and APIs, ideally in Java* Practical experience across service-based architecture, API design, integration patterns, and modern web application delivery.* Experience contributing to modernisation or platform evolution initiatives is strongly desirable.* Strong engineering discipline across testing ...

Required Technology 15+ years of progressive software engineering; 5+ years leading AI‐native solutions at enterprise scale. Hands‐on with LLMs and agentic frameworks; design and deploy AI systems that augment SDLC (requirements → coding → testing → ops). Tooling & Platforms (practitioner proficiency) Claude Code (Anthropic) for secure, context‐rich code …/Gemini for research workflows where permitted; govern enterprise knowledge ingestion. Architecture & Integration Distributed systems, microservices, cloud‐native (Azure/AWS/GCP); secure API design (REST/GraphQL). MLOps & AIOps: CI/CD for AI, model lifecycle (eval, versioning, rollout/rollback), guardrails, telemetry, drift monitoring ...

systems that enable global commerce, while evolving an existing real-time platform to support new markets. You will address backend capacity constraints and help design a shared transaction and ledger layer used across multiple business lines. This is a hands-on senior engineering role requiring both high-quality delivery … strong technical leadership in ambiguous, high-scale environments. You will be expected to: Design scalable systems with correctness and failure modes considered from the outset Clarify and scope requirements before proposing solutions Make pragmatic trade-offs in system design, avoiding over-engineering Operate independently without reliance ...

deliver against them. It is not a programme, delivery or governance position: you make the architectural calls rather than facilitate them. You will: Design large-scale agentic AI architectures: LLM document processing, structured extraction, RAG, invoice-to-contract matching Own low-level design decisions, including API design ...

using ASP.NET MVC 5, C#, and React, delivering high-quality, scalable, and maintainable code. Support the migration to new technologies, ensuring clean architecture, scalable design, and efficient implementation delivered smoothly and seamlessly. Apply SOLID principles, object-oriented design, and industry best practices to build secure, performant, and fault … with Azure ecosystem, specifically in architecting and deploying Azure App Services, Azure SQL Database, Azure Functions, and managing cloud infrastructure including Virtual Networks (VNet), API Management (APIM), and Azure Storage solutions. Minimum 8 years of digital development experience with a strong portfolio in bespoke eCommerce and enterprise web applications. ...

where correctness, transparency and performance matter. You'll have real ownership, from architecture through deployment, across new and existing products. What You'll Do Design, build and ship features across the full stack (Fastify microservices, React/MUI, shared TypeScript packages in a pnpm monorepo) Design and evolve … backend services for high-volume, distributed screening workloads Build event-driven pipelines (AWS SNS/SQS) with idempotent consumers, DLQs and batch processing Design clean APIs and contribute to architecture across multiple products Integrate external identity, KYC and payments platforms (e.g. Senzing, Auth0, Stripe) Own services ...

deployment pipelines, infrastructure as code, and GitOps practices Messaging & Events Solid grasp of messaging technologies (Kafka, RabbitMQ, SQS, NATS) and event-driven architecture patterns API Design Proven track record designing and implementing RESTful and/or GraphQL APIs that scale You may be assessed on the key critical … Barclays clients for a minimum of ten years. For more information on our partnership with Brookfield, please visit Barclays.com. Purpose of the role To design, develop and improve software, utilising various engineering methodologies, that provides business, platform, and technology capabilities for our customers and colleagues. Accountabilities Development and delivery ...

built to last and built to scale.* **Drive Scalability & Reliability.** Lead the engineering effort to make RoD elastically scalable and enterprise-grade reliable. Design for high availability, graceful degradation, and zero-downtime deployments. Define SLOs, own the SRE practice for the platform, and be accountable when things need fixing. … fully understood at all times. You will set the standard and ensure the team can operate with confidence.* **Establish End-to-End Testing.** Design and champion a robust E2E testing strategy across the platform. From contract testing at service boundaries to full integration and regression suites, you will ensure ...

Ireland providing specialist services to a wide range of blue-chip clients. The role We are seeking technical polyglots who enjoy both technical architectural design, hands-on coding and peer reviews, though also like the idea of the equally important social/client-facing aspect of the role. … development architecture as well as supporting business analysts and product owners in planning and story-mapping for new development. You will act as technical design authority (TDA) for delivery of technical stories and produce technical documentation artefacts to support the delivery process. Main Responsibilities Duties will include: The design ...

Senior Developer, Back End, API, .Net SQL, NW London to £80K (office based role) A Senior Back End Developer is required to join this established financial software house based in North London. They work with some of the leading brands in retail and media, offering financial management systems developed … required with expertise in .NET, C#/VB, SQL Server, and SAP Business One integration. The ideal candidate should have strong skills in RESTful API development, database optimization, and Azure DevOps pipeline management. Knowledge of API security, CI/CD automation, and Swagger documentation is recommended. Responsibilities API ...

Senior .Net Developer, C#/VB.Net, API, SQL, NW London to £85K A Back End Developer is required to join this established financial software house based in North London. They work with some of the leading brands in retail and media, offering financial management systems developed in house … required with expertise in Visual Basic .NET, C#, SQL Server, and SAP Business One integration. The ideal candidate should have strong skills in RESTful API development, database optimization, and Azure DevOps pipeline management. Knowledge of API security, CI/CD automation, and Swagger documentation is recommended. Responsibilities API ...

Treasury foundation that can scale with us. Your Responsibilities in this Role Own key architecture and implementation decisions for the collections & treasury foundation Lead design work (RFCs, diagrams, API and system specs) to align on solutions before building Partner with PMs and stakeholders to translate business intent into … technically sound requirements Design and build customer‐facing and internal APIs to support collections and payment strategies Build reliable infrastructure for vIBAN provisioning and collections orchestration Drive engineering quality across API standards, testing strategy, code review bar, and maintainability Manage delivery by breaking down complex work, sequencing milestones ...

deliver the roadmap for horizontal platform capabilities serving all private markets asset classes - including core data services, cross-fund analytics, workflow automation, and API infrastructure. Lead initiatives in AI/ML-enabled product features, including document extraction (e.g., fund documents, LP agreements, investment memos), NLP-powered search, and intelligent … reporting cycles. Demonstrated experience owning platform-level or infrastructure product workstreams with high technical complexity. Familiarity with data architecture concepts: data modeling, ETL pipelines, API design, and event-driven systems. Experience with agile development methodologies; strong proficiency with product management tools (Jira, Confluence, Productboard, or similar). Exceptional ...

services effectively. The role will be working closely alongside the SPM business team and technology vendors to engineer solutions supporting their strategic roadmap. Responsibilities: Design, build, and improve modern application services that support a strategic business platform, focusing on quality, maintainability, and performance. Develop backend services and APIs supporting … strong track record of delivering production systems. Strong experience building backend applications and APIs, ideally in Java. Practical experience across service‐based architecture, API design, integration patterns, and modern web application delivery. Experience contributing to modernisation or platform evolution initiatives is strongly desirable. Strong engineering discipline across testing ...

secure, and cost-efficient platform infrastructure that enables AI engineering teams to ship and operate AI products reliably in production. What you'll do Design, build, and operate cloud-native AI platform infrastructure across AWS (Lambda, API Gateway, DynamoDB, S3, CloudWatch) and Databricks Deploy and operate containerised services … workflows, and RAG components Implement observability across AI workloads using CloudWatch, MLflow, and OpenTelemetry - covering latency, throughput, cost, and system health Apply secure-by-design principles including IAM, encryption, network controls, and audit logging Work closely with AI engineers to translate prototypes and proof-of-concepts into production-ready ...

work: billing, payments, subscriber management, RADIUS‐based network authentication, and integrations with ISP billing systems and mobile money providers. We are replacing legacy, non‐API systems with a modern API platform, and real money is already flowing through the system. This is a small, high‐intensity engineering team … when they hit technical walls. You will not manage people. You will build systems. What you will own Payments domain: SasaPay collections integration (C2B API, STK push, IPN handling), revenue split engine (per‐partner, per‐BNG percentage logic), ChoiceBank treasury operations (withdrawals, internal transfers, OTP flows), and the payment ...

Solirius Reply, part of the Reply Group, is a technology consultancy and digital transformation partner that helps organisations solve complex challenges through strategy, design, engineering, and delivery. We work closely with our clients to deliver secure, accessible, user-focused services that evolve with their needs. By combining deep technical … expertise with people-centred design, we create solutions that deliver meaningful, lasting impact. Our consultants partner directly with client teams, embedding into organisations to understand their goals, challenges, and users. This collaborative approach enables us to deliver tailored solutions that drive measurable outcomes across public and private sectors. Past ...

role is hybrid working (1-2 days on site per week), with preferred location of Sheffield but London may also be possible. Key Responsibilities Design, develop, and maintain scalable software solutions across frontend and backend services. Contribute to the delivery of key product and project milestones as part … across both frontend and backend technologies. Proven experience with modern frontend frameworks such as React, Vue, Angular, or similar. Strong backend development skills, including API design and service-based architecture. Proficiency in one or more backend languages such as Python, Node.js, Java, or equivalent. Hands-on experience with ...

foundational systems that power our embedded finance platform at global scale. The team owns multi‐tenant infrastructure, drives cross‐domain product capabilities, and helps design technical solutions for enterprise customers. Key areas of ownership include: Embedded Finance Platform: Build and maintain the infrastructure powering customers like Rippling, Navan, Qantas … career development. Set technical direction for scalable, reliable backend systems and partner with senior engineers on architecture and design. Ensure high standards for system design, code quality, testing, and operational excellence. Drive improvements across reliability, observability, security, and developer productivity. Work cross‐functionally with product, design, compliance, sales ...

senior, individual engineers have outsized impact which is exactly why ownership matters so much in this role. What you'll own Backend & architecture. Design, build and evolve the services, APIs, data pipelines and scoring/recommendation logic at the core of the product owning architecture, infrastructure, schema design … looking for Must-haves Strong full-stack/backend engineering. 5+ years of professional software development (stack flexible) with strong server-side fundamentals API design, data modelling/schema design, authentication patterns and clean service architecture. Comfortable across SQL databases and a modern backend stack (e.g. Python ...

engineers have outsized impact – which is exactly why ownership matters so much in this role. \n What you'll own \n \n Backend & architecture. Design, build and evolve the services, APIs, data pipelines and scoring/recommendation logic at the core of the product – owning architecture, infrastructure, schema design … Must-haves \n \n Strong full-stack/backend engineering. 5+ years of professional software development (stack flexible) with strong server-side fundamentals – API design, data modelling/schema design, authentication patterns and clean service architecture. Comfortable across SQL databases and a modern backend stack (e.g. Python ...

skilled Sr. Delivery Consultant to join our team at Amazon Web Services (AWS). In this role, you will work closely with customers to design, implement, and manage AWS solutions that meet their technical requirements and business objectives. You will be a key player in driving customer success throughout … here: https://www.gov.uk/government/publications/united-kingdom-security-vetting-clearance-levels Basic Qualifications Experience as a technical specialist in design and architecture. Experience in cloud-based solution (AWS or equivalent), system, network, and operating system. Experience in external or internal customer-facing, complex ...

Boomi AtomSphere, connecting multiple enterprise platforms across cloud and on-premise environments. This is a hands-on technical position requiring strong Boomi development experience, API integration knowledge and the ability to support complex integration landscapes.Key Responsibilities:Design and develop scalable integration solutions using Dell Boomi AtomSphere, including process … manage secure Managed File Transfer (MFT) workflows to support high-volume and sensitive data transfersPublish, secure and govern REST/SOAP APIs through Boomi API Management, including gateway configuration, throttling and developer portal managementDevelop and maintain CI/CD pipelines using Git, Azure DevOps or Jenkins, supporting automated testing ...