1 to 25 of 42 API Design Jobs in London

Boomi Architect

Hiring Organisation
Syntax Consultancy Ltd
Location
London, United Kingdom
Employment Type
Contract
Contract Rate
£500/day 500/day (Outside IR35)
. Start ASAP during Summer 2026. Key skills, experience + tasks will include: Boomi Solution Architect with a strong focus on Boomi/iPaaS, API Management, Event Streaming, integration architecture, governance + technical leadership. Integration Adoption & Project Onboarding - architecture engagement + onboarding of priority projects onto the strategic integration … platform (e.g. SDEC, S4H, DWIT). Production of project-specific integration designs aligned to approved iPaaS, API and Streaming patterns. Completion of architecture assurance reviews and design recommendations for onboarding projects. Support projects through technical discovery, design and implementation phases. Reusable Integration Asset Library: design ...

Integration Architect - Java, AWS, FS - OutsideIR35

Hiring Organisation
Sanderson Recruitment
Location
City of London, London, United Kingdom
Employment Type
Contract
Contract Rate
£550 - £600 per day + Outside IR35
connectivity across the clients core systems. Key Responsibilities: Own and evolve integration architecture aligned with enterprise standards Define and govern integration patterns across teams Design and deliver event-driven, API-first, and messaging solutions (NATS, REST) Lead end-to-end integration delivery, including hands-on development (Java/… Spring) Ensure scalable, cloud-native solutions on AWS Produce architecture artefacts (blueprints, contracts, ADRs) Guide teams on best practices, API governance, and event design Engage stakeholders and align cross-team integration efforts Primary Skills: Event-driven architecture and messaging systems (NATS, pub/sub, async patterns) API ...

Integration Architect - Java, AWS, FS - OutsideIR35

Hiring Organisation
Sanderson
Location
London, South East, England, United Kingdom
Employment Type
Contractor
Contract Rate
£550 - £600 per day
connectivity across the clients core systems. Key Responsibilities: Own and evolve integration architecture aligned with enterprise standards Define and govern integration patterns across teams Design and deliver event-driven, API-first, and messaging solutions (NATS, REST) Lead end-to-end integration delivery, including hands-on development (Java/… Spring) Ensure scalable, cloud-native solutions on AWS Produce architecture artefacts (blueprints, contracts, ADRs) Guide teams on best practices, API governance, and event design Engage stakeholders and align cross-team integration efforts Primary Skills: Event-driven architecture and messaging systems (NATS, pub/sub, async patterns) API ...

Backend Developer (Azure)

Hiring Organisation
Amtis Professional Ltd
Location
London, Euston, United Kingdom
Employment Type
Contract
Contract Rate
£425 - £475/day OUTSIDE IR35
outside IR35. This is a hands-on role working on a mature Azure-based backend platform, with responsibility across the full software lifecycle - from design and development through to testing, deployment and production support. You’ll be working with C#, .NET, Azure Functions, Azure SQL, Azure Service Bus, Azure … API Management and Azure DevOps, contributing to a platform that supports connected patient services. This role is particularly suited to a developer who can hit the ground running, work independently and own technical delivery end-to-end without requiring day-to-day technical supervision. What You’ll Be Doing ...

Senior Java Developer

Hiring Organisation
CODEVERSE LIMITED
Location
London, South East, England, United Kingdom
Employment Type
Contractor
Contract Rate
£300 - £400 per day
experienced Senior Java/Python Engineer to join a high-performing Agile engineering team delivering secure, highly available and scalable microservices and API platforms. You will be hands-on with modern engineering technologies, working across microservices, APIs, Kafka, cloud databases, containers and observability, while also providing technical leadership … mentoring junior engineers. Key Responsibilities Design and develop scalable Java/Python microservices and REST APIs. Build and operate event-driven solutions using Apache Kafka . Design and optimise AWS Aurora PostgreSQL databases and data platforms. Deploy and support applications using Docker and Kubernetes . Develop API ...

Manager - Lead AI Engineer

Hiring Organisation
KPMG UK
Location
City of London, London, United Kingdom
Data Analytics, and Software Development, the team is revolutionising the auditing process to deliver smarter, faster, and more reliable outcomes. Our mission is to design and implement robust, intelligent, and scalable technologies that not only streamline workflows but also enhance audit quality and generate actionable insights for auditors … backend development as a Senior role. Languages/Frameworks: Strong proficiency in Python with hands-on experience in asynchronous programming, concurrency and multithreading. API Expertise: Proven experience in building and integrating APIs, with expertise in API documentation and schema definition using OpenAPI/Swagger. Strong understanding of RESTful ...

Fullstack Engineer (Backend)

Hiring Organisation
Randstad Technologies Recruitment
Location
London, United Kingdom
Employment Type
Contract
Contract Rate
£450 - £550/day
Opportunity You will join a high-impact development squad building commercial offerings on top of the thriving open-source Backstage framework. You will design and build backend systems, APIs, and developer portals that elevate the developer experience across external commercial clients and internal engineering teams alike. Your Impact Backend … API Systems: Design, build, and maintain scalable backend services and APIs primarily using TypeScript, Node.js, and modern web technologies. Developer Experience & Infrastructure: Build and operate infrastructure, developer toolsets, and CI/CD deployment pipelines to streamline engineering workflows. Engineering Excellence: Elevate code quality through technical RFCs, code reviews ...

Sr. Director, Onyx Application Engineering

Hiring Organisation
GSK
Location
Greater London, United Kingdom
Employment Type
Full Time
Experience leading global engineering teams across multiple geographies and cultures. Google Cloud Platform certification or comparable cloud certification. #GSK-LI Skills Application Programming Interface (API) Security, CI/CD, Cloud Engineering, Configuration Management (CM), Database Management, Data Engineering, Data Integration, Front-End Development, Internet of Things (IoT), Mobile Development … RESTful API Design, Security System Design, Software Development Life Cycle (SDLC), Version Control, Web Development Why GSK? Uniting science, technology and talent to get ahead of disease together. GSK is a global biopharma company with a purpose to unite science, technology and talent to get ahead ...

Solution Architect

Hiring Organisation
Hackajob Ltd
Location
South West London, London, United Kingdom
Employment Type
Permanent
public sector clients, helping to deliver Solirius' services to the highest standard. The role will involve working with multiple business stakeholders, helping them to design business solutions which will then be implemented by the delivery teams. As a Solution Architect, you will be expected to operate with a high … role will require innovative thinking, applying best practices and emerging technologies to solve complex business problems in creative and pragmatic ways. Requirements Key Responsibilities: Design end-to-end solution architectures that meet business, technical, and security requirements. Translate business and technical requirements into scalable, secure, and cost-effective designs. ...

Technical Lead - Java

Hiring Organisation
Sanderson Recruitment
Location
London, United Kingdom
Employment Type
Permanent
Salary
£95,000
helping shape modern platforms that leverage Agentic AI, workflow orchestration, and intelligent automation to solve complex business challenges. What You'll Do Lead the design and delivery of scalable Java 17+/Spring Boot microservices Own architecture decisions, system design, and engineering standards Design resilient, high-performance … adoption of AI engineering tools including GitHub Copilot, Cursor, and Claude Code Deliver AI-powered features using LLMs, RAG, semantic search, and intelligent automation Design workflow orchestration solutions using Camunda or similar BPM platforms Lead the implementation of Agentic AI capabilities, autonomous workflows, and AI-driven decision making Drive ...

Principal Developer

Hiring Organisation
Hackajob Ltd
Location
South West London, London, United Kingdom
Employment Type
Permanent, Work From Home
Salary
£90,000
delivery methodology to ensure timely and high-quality delivery of software applications. Technical Ownership: Take technical ownership of a product or software solution, covering design, estimation, shaping, and user story/requirement creation. Solution Documentation: Document solutions, including architecture, configuration, release, and support handover. Stakeholder Collaboration: Collaborate and liaise … practices and modern architectural patterns, including microservices and message-driven architectures. Non-Functional Requirements: Experience developing applications with non-functional requirements in mind. Application Design: Experience in application/digital services design. Software Engineering Practices: Proficiency in software engineering practices like code reviews, CI/CD pipelines, and SOLID ...

Systems Developer

Hiring Organisation
Massenhove Recruitment Limited
Location
City of London, London, England, United Kingdom
Employment Type
Full-Time
Salary
£40,000 - £55,000 per annum
insurers alike. Ideal for a candidate who is driven to succeed, take ownership and pride in delivering exceptional levels of customer service. Key Accountabilities Design, develop, test, and maintain Python applications, scripts, and services Build and maintain APIs and integrations with third-party systems and internal platforms Write clean … technical solutions Participate in code reviews, sprint planning, and agile ceremonies Troubleshoot, debug, and resolve production issues in a timely manner Contribute to the design and optimisation of data pipelines and database interactions Support CI/CD pipeline development and deployment automation Write and maintain unit, integration, and regression ...

Solutions Architect

Hiring Organisation
Euro Car Parks
Location
Central London, London, United Kingdom
Employment Type
Permanent
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 Software Engineer

Hiring Organisation
Lynx Recruitment Limited
Location
South West London, London, United Kingdom
Employment Type
Permanent
applications while collaborating with architects, engineers and stakeholders to deliver innovative digital solutions. The Role As a Senior Software Engineer, you'll lead the design and development of modern cloud-native applications, working closely with clients to understand business requirements and translate them into robust technical solutions. … contribute to solution design, mentor other engineers, promote engineering best practices, and help shape scalable, resilient platforms built on Microsoft Azure. What You'll Be Doing Design, develop and deliver modern cloud-native applications. Build scalable, secure and resilient event-driven solutions. Develop production-quality software using .NET ...

Senior Software Engineer

Hiring Organisation
Lynx Recruitment Ltd
Location
London, South East, England, United Kingdom
Employment Type
Full-Time
Salary
£75,000 - £105,000 per annum
applications while collaborating with architects, engineers and stakeholders to deliver innovative digital solutions. The Role As a Senior Software Engineer, you'll lead the design and development of modern cloud-native applications, working closely with clients to understand business requirements and translate them into robust technical solutions. … contribute to solution design, mentor other engineers, promote engineering best practices, and help shape scalable, resilient platforms built on Microsoft Azure. What You'll Be Doing Design, develop and deliver modern cloud-native applications. Build scalable, secure and resilient event-driven solutions. Develop production-quality software using .NET ...

Engineering Lead - Financial Planning (iRESS Xplan)

Hiring Organisation
Experis
Location
London, United Kingdom
Employment Type
Permanent
Salary
£90000 - £115000/annum
role in shaping the future technology landscape supporting advisers and clients across the organisation. The Role As Engineering Lead, you'll own the design, development, integration and operation of the firm's financial planning platform, ensuring it remains scalable, secure and fit for future growth. You'll provide technical … senior technical authority for the financial planning domain. Define and maintain engineering standards covering code quality, documentation, testing and release management. Lead architecture and design decisions, ensuring scalability, maintainability and security. Conduct technical design reviews and provide expert guidance across engineering teams. Balance delivery objectives with technical debt ...

Junior Solution Architect

Hiring Organisation
Hackajob Ltd
Location
South West London, London, United Kingdom
Employment Type
Permanent, Work From Home
Salary
£55,000
public sector clients, helping to deliver Solirius services to the highest standard. The role will involve working with multiple business stakeholders, helping them to design business solutions which will then be implemented by the delivery teams. As a Junior Solution Architect, you will undertake structured analysis of technical issues … translating this analysis into designs that describe a solution. You will be consulted on design and can provide design patterns. You will identify the deeper issues that need fixing and look for opportunities to collaborate and reuse components, communicating with both technical and non-technical stakeholders. You will ...

Front End React Developer

Hiring Organisation
Ascend Consulting
Location
North West London, London, England, United Kingdom
Employment Type
Full-Time
Salary
£40,000 - £80,000 per annum
will coordinate with the rest of the team working on different layers of the infrastructure. Therefore, a commitment to collaborative problem solving, sophisticated design, and quality product is important. Responsibilities Working in a team of Front-End engineers Writing clear & concise code Working closely with Back-End engineers Participate … architecture design code reviews API design with the Back-End engineers and other team members to establish more functional, cohesive code Create, maintain documentation while implementing the best coding practices standards Hands-on approach Participation in sprint rituals What you’ll need 6+ years experience developing large ...

Senior Full Stack Java Developer

Hiring Organisation
Hackajob Ltd
Location
South West London, London, United Kingdom
Employment Type
Permanent, Work From Home
Salary
£80,000
security etc). Working within a project management/agile delivery methodology Experience in technical ownership for a product or software solution, covering design, estimation, shaping and user story/requirement creation Documentation of solutions (e.g. architecture, configuration, release, support-handover Collaborate and liaise with other Version … including microservices and message-driven architectures NFR/Non-Functional requirement understanding and experience developing applications with this in mind Application/Digital Services Design experience Experience in software engineering practices like Code Reviews, CI/CD Pipelines and SOLID/DRY principals Hands-on developing/coding role ...

Product Engineer (Internal tools & apps)

Hiring Organisation
Hackajob Ltd
Location
South West London, London, United Kingdom
Employment Type
Permanent
Slack and React: the agents people talk to and the apps they click through, built in TypeScript. And you don't stop there. From API and MCP design to infrastructure on Vercel, AWS, Supabase, and BigQuery, plus the agents that work across the stack, you own complete features … software factory. What you'll bring 5+ years of experience building applications or tooling that automate human workflows Full-stack experience across the board: API design, databases, async workflows and background jobs on the backend, and clean, user-friendly UX on the frontend. Being AI-native. An early ...

Senior C# Engineer .NET 9/10, AWS Lambda, SQS, SNS Outside IR35

Hiring Organisation
Smart Sourcer Limited
Location
City of London, London, United Kingdom
Employment Type
Contract
Contract Rate
From £700 to £800 per day
Overview: Youll operate as the technical spearhead for a greenfield product build, reporting to the Director of Engineering. Expect deep backend engineering, distributed system design, and high-quality serverless delivery, plus the chance to adopt modern AI-assisted development practices as part of your workflow. What Youll Bring: Senior … ability to architect and lead distributed REST microservices at scale. Strong authority in AWS serverless engineering: Lambda-first mindset, hands-on experience with API Gateway, SQS, Step Functions, EventBridge and IAM. Deep data expertise across Aurora MySQL and DynamoDB: schema design, access patterns, indexing, query tuning, and pragmatic ...

Senior Application Security Engineer / DevSecOps Engineer

Hiring Organisation
Additional Resources
Location
London, United Kingdom
Employment Type
Permanent
Salary
£80000 - £90000/annum
teams to integrate security throughout the software development lifecycle. Microsoft Azure and KQL experience are essential, alongside relevant experience in CI/CD, Kubernetes, API security, security-as-code and security automation. This is a hands-on application security role focused on secure design, application security testing … Integrating security controls into CI/CD pipelines. Strengthening the security of GitHub Actions and similar CI/CD platforms. Providing guidance on secure API design and externally accessible systems. Supporting Azure cloud infrastructure, including Azure Kubernetes Service (AKS). Developing security-as-code and policy-as-code. ...

UI Senior Lead Software Engineer - Commodities

Hiring Organisation
Hackajob Ltd
Location
South West London, London, United Kingdom
Employment Type
Permanent
inclusive team culture. This role emphasizes engineering excellence, operational readiness, and secure, compliant delivery in a fast-paced global environment. Job Responsibilities Lead the design and delivery of user interface capabilities across Execute, from discovery to production support Set front-end technical direction, including architecture, standards, performance, and testing … leadership in setting standards, leading designs, and directly managing or mentoring small teams of mid-level engineers Solid software engineering fundamentals, including OO/design patterns, debugging, and documentation Familiarity with agentic development approaches across the software development lifecycle Strong communication and people skills, with the ability to work ...

Contract AI Software Engineer - DV Cleared

Hiring Organisation
NSD
Location
City of London, London, United Kingdom
Employment Type
Contract, Work From Home
Contract Rate
£450 - £650 per day
Experience with AWS or Azure Familiarity with Docker and Kubernetes Experience working in secure or highly regulated environments Strong understanding of software architecture and API design IT WOULD BE NICE FOR THE AI SOFTWARE ENGINEER TO HAVE. Experience with RAG pipelines and vector databases Knowledge of MLOps tooling ...

Senior Software Engineer

Hiring Organisation
XCEEDANCE LIMITED
Location
London Area, United Kingdom
skilled Java Software Engineer with a growing interest and demonstrated exposure to AI/ML integration. This role is primarily Java-centric — you will design and build cloud-native microservices on our BPA (Beyond Policy Administration) platform — with the expectation that you actively apply AI tooling and patterns … prototype level. Role Details Location: London Experience: 4–7 years of overall software engineering experience Engagement Model: Full-time, Product Engineering Job Responsibilities Design and implement RESTful APIs and microservices using Java 17+ and Spring Boot 3.x. Build and maintain business logic within the BPA platform, ensuring correctness, performance ...