26 to 48 of 48 API Design Jobs in London

Principal Technical Lead

Hiring Organisation
RSSB
Location
City of London, London, United Kingdom
Employment Type
Contract, Work From Home
delivery of the platform, ensuring the team consistently ships high-quality, production-ready increments. Ensure engineering standards are followed across the team: coding conventions, API design, security practices, and code review processes. Lead estimation, sprint planning, and decomposition of technical work; proactively identify and manage technical risk, dependencies … architecture function, clearly articulating technical constraints, risks, or emerging complexity with architectural implications, supported by evidence and proposed alternatives. Ensure application of secure-by-design principles and validate and refine Figma wireframes. Represent the team's technical work clearly and credibly to non-technical audiences. Define and enforce ...

Senior AI Engineer

Hiring Organisation
Cognizant
Location
City of London, London, United Kingdom
Large Language Models (LLMs), Agentic frameworks, and predictive algorithms. The ideal candidate blends software engineering discipline with a deep understanding of AI to design scalable, cost-efficient, highly reliable systems, and driving best-practice use of Databricks across the organisation. This role sets the technical foundations, standards, and patterns … experience Hands-on experience with Python frameworks such as Flask, FastAPI, or Django. Proven experience building and maintaining RESTful APIs. Solid understanding of API design, security, versioning, and scalability. Python proficiency, LLM orchestration (RAG), and hands-on experience designing end-to-end intelligent applications using Microsoft's cloud ...

Manager - Lead AI Engineer

Hiring Organisation
Anson Mccade
Location
City of London, London, United Kingdom
Employment Type
Permanent, Work From Home
Salary
£70,000
building and knowledge-sharing initiatives Skills & Experience Required Significant senior backend development experience with strong Python proficiency (async programming, concurrency, multithreading) Expertise in RESTful API design, OpenAPI/Swagger documentation and API lifecycle best practices Hands-on experience with ML libraries: PyTorch, PySpark, scikit-learn, Hugging Face … machine learning, cloud computing or data engineering highly advantageous Professional accounting qualification desirable but not required Nice to Have Experience with Microsoft Graph API Background in audit, financial services or regulated industry technology What's on Offer A competitive salary and benefits package, flexible hybrid working across 20+ ...

Software Engineer C#, React, .NET

Hiring Organisation
RX Global
Location
Greater London, United Kingdom
Employment Type
Full Time
.NET/C#,, NET Core and familiarity with SQL or data skills Proficiency in Front end tech stack React or Angular Understanding of system design, domain modelling, and API design principles Experience writing unit and integration tests and working with CI/CD pipelines Exposure to cloud ...

Senior Software Engineer – Data Visualisation & Graphics | London

Hiring Organisation
techstack Recruitment
Location
London Area, United Kingdom
working on the underlying systems that make complex visualisations fast, accurate, and scalable. The challenges range from rendering performance and interaction design through to algorithms, graphics, API design, and numerical correctness. What you’ll be doing Designing and building core charting features used by developers around … exceptionally high technical standards High levels of ownership and autonomy Small team, significant impact Opportunity to deepen expertise in performance, graphics, visualisation, and systems design Package Salary up to £200,000 Hybrid working (London) Private healthcare Pension Additional benefits If you’re interested in building the technology behind modern ...

Back-End Development Lead

Hiring Organisation
Oyster Consultant
Location
South East London, London, United Kingdom
Employment Type
Permanent, Work From Home
Salary
£80,000
evolve our stack and make constant improvements. Required Skills/Experience Strong C# development experience Experience with both .NET Core and .NET Web API Experience of building Microservices in .Net Core Experience using Message Based Architectures Experience using both SQL & NoSQL technologies Experience of API design Cloud ...

Full Stack Engineer

Hiring Organisation
Total Recruitment Group
Location
West London, London, United Kingdom
Employment Type
Permanent
Salary
£85,000
role, with strong backend expertise in Typescript and Node and front capability in React Proficiency in SQL, Redux, cloud services (AWS or GCP), RESTful API design and GraphQL Strong analytical skills with the ability to design, optimise, and troubleshoot complex UIs Excellent communication and leadership skills; ability ...

Senior Full Stack Engineer (GCP, Python, JavaScript) Remote

Hiring Organisation
Exalto Consulting
Location
London, United Kingdom
Employment Type
Contract
Contract Rate
£400 - £410/day
assisted development workflows. ● Agile Experience: Proven track record working within Agile teams and participating in iterative delivery. ● Core Engineering: Proficiency in Git, REST API design, and modern CI/CD practices This is a great opportunity to work for an exciting organisation and to start ASAP. The role ...

Lead Software Engineer

Hiring Organisation
MARSH CORPORATE SERVICES LIMITED
Location
City of London, London, United Kingdom
Employment Type
Permanent, Work From Home
products (e.g., Concierge an agentic AI workflow tool, Prism a Mercer knowledge fabric for scheme data, and similar initiatives), from problem framing and design through build, release, and support. Translate risk advisory/consulting needs into clear technical requirements, user stories, and solution designs; partner with stakeholders through … Proven experience as a Tech Lead/Lead Engineer delivering production software, including hands-on coding and code review ownership. Strong backend engineering skills (API design, data modelling, performance) and experience building secure, role-based applications. Experience working directly with business stakeholders in a financial firm, with ...

Senior Developer

Hiring Organisation
Addition
Location
London, South East, England, United Kingdom
Employment Type
Full-Time
Salary
£70,000 - £90,000 per annum
improving APIs that support critical platform functionality Investigating production issues and tracing problems across distributed systems Working with product and engineering teams to design scalable solutions Improving reliability, observability and performance across existing services Reviewing code, sharing knowledge and helping raise engineering standards across the team Tackling real-world … APIs used by customers or internal teams Other Skills Needed: Solid backend engineering experience in C#, Java, or Go, with a strong grasp of API design and architecture. Hands-on experience managing and debugging production systems across cloud and self-managed infrastructure. Proven ability to navigate complex third ...

Ruby Developer

Hiring Organisation
Proactive Appointments
Location
London, United Kingdom
Employment Type
Permanent
Salary
GBP 70,000 - 80,000 Annual
develop new features, enhance existing systems, and ensure our platform remains stable and efficient. Your deep understanding of Rails architecture, PostgreSQL optimisation, and API design will be essential as you contribute to ongoing development projects. If you enjoy collaborating in Agile/Scrum environments, value clean code ...

Ruby on Rails Backend Engineer

Hiring Organisation
Rise Technical Recruitment
Location
Fulham, London, United Kingdom
Employment Type
Permanent
Salary
£60000 - £80000/annum Private Healthcare + Holiday + Pensi
evolution of core Ruby on Rails operational platforms. Optimise PostgreSQL performance and Sidekiq background job efficiency. Manage secure third-party integrations and RESTful API design. Partner with Platform teams on AWS and CI/CD reliability. The Person: Deep experience with Ruby on Rails and OOP. Expert in PostgreSQL ...

Knowledge Graph Architect

Hiring Organisation
ARM (Advanced Resource Managers)
Location
London, United Kingdom
Employment Type
Contract
Contract Rate
GBP Annual
Knowledge Graph Architect 6 months Remote/London £Negotiable - INSIDE IR35 KEY SKILLS Neo4j schema design Ontology engineering Graph RAG API design Disclaimer: This vacancy is being advertised by either Advanced Resource Managers Limited, Advanced Resource Managers IT Limited or Advanced Resource Managers Engineering Limited ("ARM"). ...

Lead Python Developer

Hiring Organisation
Total Recruitment Group
Location
South East London, London, United Kingdom
Employment Type
Permanent
Salary
£85,000
stuck into some genuinely interesting engineering. Think computational complexity, mathematical optimisation, and performance challenges at scale - a long way from your average API job. Requirements: 7+ years experience developing and maintain scalable Python/FastAPI back-end services Ideally worked with high-performance APIs for complex hierarchical data queries … code Lead technical planning by breaking down roadmap items into scoped engineering work, driving ADRs and setting standards for code quality, testing, and API design Collaborate cross-functionally with front-end, data engineering, modelling and product teams to deliver reliable, impactful features Line-manage a team ...

Lead Full Stack Engineer

Hiring Organisation
Calyptus
Location
Greater London, England, United Kingdom
right solutions, in the right way, at the right time. What They’ll Do Own architecture and technical strategy for core domains and systems. Design, guide, and implement complex, cross-functional solutions spanning multiple areas of the product. Write high-impact code, including reference implementations, critical-path systems … Engineers will work on meaningful production challenges that combine physical systems, real-world constraints, and measurable impact, including: Heat loss modelling and hydronic system design 2D and 3D floor-plan tooling using LiDAR and computer vision Large-scale data ingestion and geospatial analysis Offline-first collaborative PWAs Hardware integrations ...

Principal Data Architect

Hiring Organisation
Experis
Location
City of London, London, United Kingdom
Employment Type
Contract
Contract Rate
£700 - £800 per day
Data platforms - Fabric, Snowflake, CosmoDB, DataBricks, MongoDB, RDBMS Data replication/CDC - Qlik Replicate, Oracle Golden Gate Data modeling - ERStudio Message-oriented data movement API design and access Data Analytics and AL/ML - AzureML Data virtualization Streaming data Data integration and ETL/ELT Tools - Matillion, Alteryx … NoSQL data stores, methods, and approaches (star and snowflake, dimensional modelling and third normal form) Experience with data security and data access controls and design Deep understanding of SoX, GDPR and Regulatory/CNI control environments In-depth experience in providing resolution to an extensive range of complicated data ...

IT Solutions Architect (Integration / Azure)

Hiring Organisation
DGH Recruitment
Location
City of London, London, United Kingdom
Employment Type
Permanent, Work From Home
that supports business critical functions across the business. My client have migrated significant services to the cloud and now requires a lead architect to design and build the next generation of solutions including core finance and HR technology landscape, automating data flows, integrating systems, supporting in the delivery … real-time reporting and analysis, whilst driving a more mature awareness to data architecture and governance across the business. Responsibilities: - Lead the design and delivery of integrations across technology platforms and solutions. - Produce architectural documentation (HLDs, LLDs, diagrams, support guides). - Ownership of integration and application architecture in alignment ...

Backend Engineer

Hiring Organisation
Robert Half
Location
London, South East, England, United Kingdom
Employment Type
Contractor
Contract Rate
Salary negotiable
Live platform Contributing to a shared transaction layer used across multiple products Collaborating with frontend and mobile engineers to deliver consistent experiences Key Responsibilities Design and build backend services end-to-end Contribute to platform and API design decisions Improve system performance and reliability Work within … evolving architecture with real production constraints Profile The Backend Engineer will have strong API and service development skills Experience working on transaction systems, payments, or eCommerce platforms is required Experience with GraphQL preferred Exposure to Elixir, Go, or similar backend technologies Ability to work effectively in ambiguous, fast-changing ...

Software Engineer

Hiring Organisation
Platform Recruitment
Location
City of London, Greater London, United Kingdom
Employment Type
Permanent
Salary
£90000 - £160000/annum
heavily backend-biased position but given the size of the team you will be working across the stack when needed Build scalable, performant systems Design and deliver end-to-end features with direct impact on customer value Work with product and ML teams to help translate abstract and complex … software function About you: Strong ability across scalable and performant systems You have a product mindset Statically typed language expertise Experience with API design Low ego and love of engineering Full details are available. Please don't hesitate to reach out for more information. ...

Senior Software Engineer II (Java/ Spring)

Hiring Organisation
Elsevier
Location
Greater London, United Kingdom
Employment Type
Full Time
Salary
100400 to 167300 EUR Annually
Senior Software Engineer II , you will work with a passionate team that delivers scalable, reliable, and innovative solutions that accelerate scientific discovery. Key responsibilities: Design and implement graph-based search services. Develop applications using Java , Spring Boot, Spring, GraphQL , and GraphQL Federation . Integrate with databases, web services … Proven track record building scalable backend systems and APIs. Strong expertise in Java and the Spring Boot ecosystem . Hands-on experience with GraphQL API and REST API design. Solid background in cloud-native architectures with AWS and Kubernetes (EKS) . An advocate of best practices for rapid ...

Senior Software Engineer I – Search and AI Platform

Hiring Organisation
Elsevier
Location
Greater London, United Kingdom
Employment Type
Full Time
Salary
86900 to 144600 EUR Annually
Senior Software Engineer II , you will work with a passionate team that delivers scalable, reliable, and innovative solutions that accelerate scientific discovery. Key responsibilities: Design and implement graph-based search services. Develop applications using Java , Spring Boot, Spring, GraphQL , and GraphQL Federation . Integrate with databases, web services … Proven track record building scalable backend systems and APIs. Strong expertise in Java and the Spring Boot ecosystem . Hands-on experience with GraphQL API/REST APIs design. Solid background in cloud-native architectures with AWS and Kubernetes (EKS) . An advocate of best practices for rapid development ...

AWS Technical Architect

Hiring Organisation
Opus Recruitment Solutions
Location
Remote work, South Bank, Greater London, United Kingdom
Employment Type
Contract
Contract Rate
£0 - £600/day
/Public Sector client on a long-term contract. Key Details: You'll be working within a large-scale public sector environment, helping to design and shape modern, scalable architectures that support critical government services. Experience Cloud & architecture expertise - strong AWS architecture experience, including event-driven systems (e.g. Kafka … RESTful API design. Data & public sector experience - experience with document-based databases (e.g. MongoDB) and a solid understanding of public sector governance and assurance processes. Strong technical architecture background - experience designing secure, scalable systems using modern technologies (cloud, open source, and languages like Java, Python, JavaScript or Ruby). ...

Full Stack Engineer

Hiring Organisation
TOTTENHAM HOTSPUR FOOTBALL & ATHLETIC CO LTD
Location
Enfield, London, United Kingdom
Employment Type
Permanent
where your decisions matter. The data you work with is as rich and complex as it gets in professional sport. Key Responsibilities Application Development Design, build and maintain internal web applications across the full stack, from database to UI. Own the frontend experience on the products you work … code quality in your team. Data and Infrastructure Work directly with data engineers to understand data models, query patterns and pipeline outputs. Design and build efficient API layers that expose complex data in a way that is fast, reliable and easy to consume. Take ownership of cloud infrastructure ...