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- The City, City (EC4)
- Shoreditch
- Southwark
- Bellfields
- Causeway
- Covent Garden
- Datchet Common
- Euston
- Freshbrook
- Keeley Green
- City of London
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- Central London
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- South East London
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- East London
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12 Permanent API jobs in Wallingford + 20 miles
245 exact matches jobs are outside your preferred location
LSEG (London Stock Exchange Group) is more than a diversified global financial markets infrastructure and data business. We are dedicated, open-access partners with a dedication to excellence in delivering the services our customers expect from us. With extensive experience, deep knowledge and worldwide presence across financial markets, we enable businesses and economies around the world to fund innovation, manage risk and create jobs. Its how weve contributed to supporting the financial stability and growth of communities and economies globally for more than 300 years. Through a comprehensive suite of trusted financial market infrastructure services and our open-access model we provide the flexibility, stability and trust that enable our customers to pursue their ambitions with confidence and clarity.
LSEG (London Stock Exchange Group) is more than a diversified global financial markets infrastructure and data business. We are dedicated, open-access partners with a dedication to excellence in delivering the services our customers expect from us. With extensive experience, deep knowledge and worldwide presence across financial markets, we enable businesses and economies around the world to fund innovation, manage risk and create jobs. Its how weve contributed to supporting the financial stability and growth of communities and economies globally for more than 300 years. Through a comprehensive suite of trusted financial market infrastructure services and our open-access model we provide the flexibility, stability and trust that enable our customers to pursue their ambitions with confidence and clarity.
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FTSE Russell | LSEG Technology - FTSE Russell is a leading global provider of financial services, specializing in the creation and management of indexes, data, and analytic solutions. A subsidiary of the London Stock Exchange Group (LSEG), FTSE Russell supports investors worldwide in making informed decisions across asset classes, investment strategies, and market segments. Its products are trusted by institutional and retail investors, asset managers, and pension funds to benchmark performance, build investment portfolios, and manage risk. With a reputation for innovation, transparency, and robust governance, FTSE Russell plays a critical role in shaping global financial markets. FTSE Russell is seeking a junior software engineer to be part a dynamic team building the distribution capabilities of our index products to the financial community worldwide.
FTSE Russell | LSEG Technology - FTSE Russell is a leading global provider of financial services, specializing in the creation and management of indexes, data, and analytic solutions. A subsidiary of the London Stock Exchange Group (LSEG), FTSE Russell supports investors worldwide in making informed decisions across asset classes, investment strategies, and market segments. Its products are trusted by institutional and retail investors, asset managers, and pension funds to benchmark performance, build investment portfolios, and manage risk. With a reputation for innovation, transparency, and robust governance, FTSE Russell plays a critical role in shaping global financial markets. FTSE Russell is seeking a junior software engineer to be part a dynamic team building the distribution capabilities of our index products to the financial community worldwide.
FTSE Russell | LSEG Technology - FTSE Russell is a leading global provider of financial services, specializing in the creation and management of indexes, data, and analytic solutions. A subsidiary of the London Stock Exchange Group (LSEG), FTSE Russell supports investors worldwide in making informed decisions across asset classes, investment strategies, and market segments. Its products are trusted by institutional and retail investors, asset managers, and pension funds to benchmark performance, build investment portfolios, and manage risk. With a reputation for innovation, transparency, and robust governance, FTSE Russell plays a critical role in shaping global financial markets. FTSE Russell is seeking a senior software engineer to be part a dynamic team of software engineers building all distribution capabilities of our index products to the financial community wor
FTSE Russell | LSEG Technology - FTSE Russell is a leading global provider of financial services, specializing in the creation and management of indexes, data, and analytic solutions. A subsidiary of the London Stock Exchange Group (LSEG), FTSE Russell supports investors worldwide in making informed decisions across asset classes, investment strategies, and market segments. Its products are trusted by institutional and retail investors, asset managers, and pension funds to benchmark performance, build investment portfolios, and manage risk. With a reputation for innovation, transparency, and robust governance, FTSE Russell plays a critical role in shaping global financial markets. FTSE Russell is seeking a senior software engineer to be part a dynamic team of software engineers building all distribution capabilities of our index products to the financial community wor
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Hybrid: London (1-2 days per week in the office) Paying up to £70,000 + benefits - Permanent - Experis are delighted to be supporting a well-established and reputable organisation as they continue to strengthen and modernise their digital client-facing capabilities. We are assisting them in the search for a Seismic Developer, a key role within the Brand & Digital Services division, responsible for designing and developing advanced Seismic LiveDoc solutions that enhance client experience, streamline document creation, and enable front-office teams to work more efficiently. This is a fantastic opportunity for someone with deep Seismic expertise who enjoys building automated, scalable, and visually polished documentation solutions. You'll join an experienced team of Seismic specialists in a highly collaborative environment, supporting a well-embedded and strategically im
Hybrid: London (1-2 days per week in the office) Paying up to £70,000 + benefits - Permanent - Experis are delighted to be supporting a well-established and reputable organisation as they continue to strengthen and modernise their digital client-facing capabilities. We are assisting them in the search for a Seismic Developer, a key role within the Brand & Digital Services division, responsible for designing and developing advanced Seismic LiveDoc solutions that enhance client experience, streamline document creation, and enable front-office teams to work more efficiently. This is a fantastic opportunity for someone with deep Seismic expertise who enjoys building automated, scalable, and visually polished documentation solutions. You'll join an experienced team of Seismic specialists in a highly collaborative environment, supporting a well-embedded and strategically im
FEATURED
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Full Stack Software Engineer - Central London (1 day a month) Circa £80,000 (depending on experience) + excellent benefits package - My client are a start-up created within and as part of a large wealth management firm, so you have all the benefits of a start-up environment without the instability and inconveniences! It's an exciting environment where you'll be working with a cutting-edge tech stack creating data-driven fintech software for major financial firms. What will you do in the role? You'll be part of a high-quality Software Engineering team working with the latest tech to integrate my client's new, bespoke, in-house wealth management software with a queue of new clients while starting to plan for V2, alongside contributing your own ideas for future functions and improvements. You'll have a specific focus on CI/CD pipelines and the deployment process, reviewi
Full Stack Software Engineer - Central London (1 day a month) Circa £80,000 (depending on experience) + excellent benefits package - My client are a start-up created within and as part of a large wealth management firm, so you have all the benefits of a start-up environment without the instability and inconveniences! It's an exciting environment where you'll be working with a cutting-edge tech stack creating data-driven fintech software for major financial firms. What will you do in the role? You'll be part of a high-quality Software Engineering team working with the latest tech to integrate my client's new, bespoke, in-house wealth management software with a queue of new clients while starting to plan for V2, alongside contributing your own ideas for future functions and improvements. You'll have a specific focus on CI/CD pipelines and the deployment process, reviewi
Location: London - 1x a month - Salary: Up to £120,000 (D.O.E) + benefits - Fruition Group are partnering with a high-growth Insurtech unicorn that's scaling its engineering function. This is a unique chance to work across both proven, revenue-generating products and greenfield initiatives that are reshaping the future of insurance. It's an ideal role for a driven Lead Engineer who thrives in ambitious environments and wants to make a tangible impact. As a Lead Backend Engineer, you'll take ownership of designing and scaling cloud-native backend systems. You'll work primarily with Python (FastAPI) and play a key role in shaping the architecture of microservices that support millions of users. Beyond hands-on development, you'll provide technical leadership, mentor team members, and influence strategic engineering decisions.
Location: London - 1x a month - Salary: Up to £120,000 (D.O.E) + benefits - Fruition Group are partnering with a high-growth Insurtech unicorn that's scaling its engineering function. This is a unique chance to work across both proven, revenue-generating products and greenfield initiatives that are reshaping the future of insurance. It's an ideal role for a driven Lead Engineer who thrives in ambitious environments and wants to make a tangible impact. As a Lead Backend Engineer, you'll take ownership of designing and scaling cloud-native backend systems. You'll work primarily with Python (FastAPI) and play a key role in shaping the architecture of microservices that support millions of users. Beyond hands-on development, you'll provide technical leadership, mentor team members, and influence strategic engineering decisions.
Location: London - 1x a month - Salary: Up to £95,000 (D.O.E) + benefits - Fruition Group working with a leading Insurtech unicorn on a mission to transform the insurance industry. Their products have already generated millions in revenue, and now they're investing heavily in new innovations that will shape the sector for years to come. This is an exciting opportunity for a motivated Senior Engineer who wants to grow in a high-performing, forward-thinking business. As a Senior Backend Engineer, you'll play a central role in building and scaling the systems that power their insurance platform. You'll focus on developing Python-based cloud microservices (FastAPI preferred), contributing to the architecture of resilient, high-performance systems, and collaborating with a cross-functional team to deliver features at pace.
Location: London - 1x a month - Salary: Up to £95,000 (D.O.E) + benefits - Fruition Group working with a leading Insurtech unicorn on a mission to transform the insurance industry. Their products have already generated millions in revenue, and now they're investing heavily in new innovations that will shape the sector for years to come. This is an exciting opportunity for a motivated Senior Engineer who wants to grow in a high-performing, forward-thinking business. As a Senior Backend Engineer, you'll play a central role in building and scaling the systems that power their insurance platform. You'll focus on developing Python-based cloud microservices (FastAPI preferred), contributing to the architecture of resilient, high-performance systems, and collaborating with a cross-functional team to deliver features at pace.
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Lead PHP Developer
Lead PHP Developer
Rise Technical Recruitment Limited
Swindon (SN1)
£55000.00 - £65000.00 per annum + Bonus + Progression
Swindon (Hybrid - 3 days per-week) £55,000 - £65,000 + Bonus + Progression + Pension - An excellent opportunity awaits a Software Developer with strong PHP experience to join a growing technology-first business. The role offers technical variety, ownership and clear progression opportunities. This company is an established but expanding B2B business, with technology as its key differentiator they're looking to further grow and diversify their SaaS solutions offering. In this role, you'll take ownership of both new and existing systems, maintaining legacy code where needed while leading the design and development of new solutions. You'll work closely with the Head of Software to align on technical direction, while taking the hands-on lead in building and improving Laravel-based applications, managing APIs and third-party integrations.
Swindon (Hybrid - 3 days per-week) £55,000 - £65,000 + Bonus + Progression + Pension - An excellent opportunity awaits a Software Developer with strong PHP experience to join a growing technology-first business. The role offers technical variety, ownership and clear progression opportunities. This company is an established but expanding B2B business, with technology as its key differentiator they're looking to further grow and diversify their SaaS solutions offering. In this role, you'll take ownership of both new and existing systems, maintaining legacy code where needed while leading the design and development of new solutions. You'll work closely with the Head of Software to align on technical direction, while taking the hands-on lead in building and improving Laravel-based applications, managing APIs and third-party integrations.
PREMIUM
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We're seeking an experienced Senior Full Stack Developer to join our clients expanding technology team. In this role, you'll be instrumental in designing, developing, and maintaining high-quality, scalable web applications. You'll work across the full stack, collaborating closely with colleagues to deliver impactful, user-focused solutions. Key Responsibilities * Develop and maintain modern web applications using C# .NET (Core/Framework) and React. * Work with cross-functional teams to define requirements and deliver new features. * Write clean, scalable, and well-tested code. * Diagnose and resolve application issues to ensure optimal performance. You will have - * 3+ years' experience as a Full Stack Developer. * Strong hands-on expertise with C# .NET (Core) and React. * Good understanding of REST APIs, SQL/NoSQL databases, and Git version control.
We're seeking an experienced Senior Full Stack Developer to join our clients expanding technology team. In this role, you'll be instrumental in designing, developing, and maintaining high-quality, scalable web applications. You'll work across the full stack, collaborating closely with colleagues to deliver impactful, user-focused solutions. Key Responsibilities * Develop and maintain modern web applications using C# .NET (Core/Framework) and React. * Work with cross-functional teams to define requirements and deliver new features. * Write clean, scalable, and well-tested code. * Diagnose and resolve application issues to ensure optimal performance. You will have - * 3+ years' experience as a Full Stack Developer. * Strong hands-on expertise with C# .NET (Core) and React. * Good understanding of REST APIs, SQL/NoSQL databases, and Git version control.
We're seeking an experienced Senior Full Stack Developer to join our clients expanding technology team. In this role, you'll be instrumental in designing, developing, and maintaining high-quality, scalable web applications. You'll work across the full stack, collaborating closely with colleagues to deliver impactful, user-focused solutions. Key Responsibilities * Develop and maintain modern web applications using C# .NET (Core/Framework) and React. * Work with cross-functional teams to define requirements and deliver new features. * Write clean, scalable, and well-tested code. * Diagnose and resolve application issues to ensure optimal performance. You will have - * 3+ years' experience as a Full Stack Developer. * Strong hands-on expertise with C# .NET (Core) and React. * Good understanding of REST APIs, SQL/NoSQL databases, and Git version control.
We're seeking an experienced Senior Full Stack Developer to join our clients expanding technology team. In this role, you'll be instrumental in designing, developing, and maintaining high-quality, scalable web applications. You'll work across the full stack, collaborating closely with colleagues to deliver impactful, user-focused solutions. Key Responsibilities * Develop and maintain modern web applications using C# .NET (Core/Framework) and React. * Work with cross-functional teams to define requirements and deliver new features. * Write clean, scalable, and well-tested code. * Diagnose and resolve application issues to ensure optimal performance. You will have - * 3+ years' experience as a Full Stack Developer. * Strong hands-on expertise with C# .NET (Core) and React. * Good understanding of REST APIs, SQL/NoSQL databases, and Git version control.
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Our Purpose - Mastercard powers economies and empowers people in 200+ countries and territories worldwide. Together with our customers, were helping build asustainableeconomy where everyone can prosper. We support a wide range of digital payments choices, making transactionssecure, simple, smart and accessible. Our technology and innovation, partnerships and networks combine to deliver a unique set of products and services that help people, businesses and governments realize their greatest potential. Title and Summary - Overview - We are looking for a software engineer to join an award winning team with a proven track record of combining data science techniques with an intimate knowledge of payments data to aid Financial Institutions in their fight against money laundering and fraud. Headquartered in The City of London, we craft bespoke services that help our clients
Our Purpose - Mastercard powers economies and empowers people in 200+ countries and territories worldwide. Together with our customers, were helping build asustainableeconomy where everyone can prosper. We support a wide range of digital payments choices, making transactionssecure, simple, smart and accessible. Our technology and innovation, partnerships and networks combine to deliver a unique set of products and services that help people, businesses and governments realize their greatest potential. Title and Summary - Overview - We are looking for a software engineer to join an award winning team with a proven track record of combining data science techniques with an intimate knowledge of payments data to aid Financial Institutions in their fight against money laundering and fraud. Headquartered in The City of London, we craft bespoke services that help our clients
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Solution Architect
Solution Architect
Henderson Scott
North West London, London, NW1 7AW
£70000.00 - £75000.00 per annum + Highly Remote, 30 days AL+BH
Maintain and enforce standards for API design, integration patterns, data schemas (including Medallion architecture), and security (RBAC, data classification).
Maintain and enforce standards for API design, integration patterns, data schemas (including Medallion architecture), and security (RBAC, data classification).
FEATURED
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The successful applicant will have comprehensive expertise in Microsoft Azure services, Web API, Azure App Service, .NET Core, and Visual Studio. * Design and implement scalable cloud solutions utilizing Azure App Service, Web API, and .NET Core. * Define architecture patterns for microservices, API management, and integration with enterprise systems. * Utilize Azure Functions, Azure Logic Apps, Azure API Management, and Azure Storage to develop robust applications. * Expertise in Microsoft Azure services, including App Service, Functions, API Management, Storage, and Networking. * Strong knowledge of .NET Core, Web API, C#, and Visual Studio.
The successful applicant will have comprehensive expertise in Microsoft Azure services, Web API, Azure App Service, .NET Core, and Visual Studio. * Design and implement scalable cloud solutions utilizing Azure App Service, Web API, and .NET Core. * Define architecture patterns for microservices, API management, and integration with enterprise systems. * Utilize Azure Functions, Azure Logic Apps, Azure API Management, and Azure Storage to develop robust applications. * Expertise in Microsoft Azure services, including App Service, Functions, API Management, Storage, and Networking. * Strong knowledge of .NET Core, Web API, C#, and Visual Studio.
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Full Stack Engineer Python TypeScript
Full Stack Engineer Python TypeScript
Client Server
St James, South West London (SW1), SW1A
£100000 - £120000 per annum + bonus + benefits
You have strong backend Python coding skills, including API development
You have strong backend Python coding skills, including API development
NEWPREMIUM
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Senior Backend Engineer
Senior Backend Engineer
Plexus Resource Solutions Ltd
City of London (EC1)
From £60,000 to £100,000 per annum
Use Rest API with Python
Use Rest API with Python
The Service is one of the fastest growing streams in the LCH business lines and is looking to build on recent successes and further increase market share through modernising and enhancing our external facing application and API by delivering powerful and scalable functionality to meet evolving market demands.
The Service is one of the fastest growing streams in the LCH business lines and is looking to build on recent successes and further increase market share through modernising and enhancing our external facing application and API by delivering powerful and scalable functionality to meet evolving market demands.
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Expertise in system and API design, scalability, and performance tuning
Expertise in system and API design, scalability, and performance tuning
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Senior Frontend Developer
Senior Frontend Developer
Pathfinder Business Solutions Ltd
Milton Keynes (MK9), MK9 3QA
From £50,000 to £60,000 per annum Full Benefits Pack
REST-based API development
REST-based API development
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Senior Full Stack Engineer
Senior Full Stack Engineer
McGregor Boyall Associates Limited
City of London (EC1)
£80000 - £120000 per annum + bonus
Strong knowledge of system design principles, scalable architecture patterns, and API design.
Strong knowledge of system design principles, scalable architecture patterns, and API design.
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Experience building maintainable and testable code bases, including API design and unit testing techniques
Experience building maintainable and testable code bases, including API design and unit testing techniques
Build, fine-tune, and evaluate LLM-based Q&A models using frameworks like AWS Bedrock, Langchain, HuggingFace Transformers or OpenAI API.
Build, fine-tune, and evaluate LLM-based Q&A models using frameworks like AWS Bedrock, Langchain, HuggingFace Transformers or OpenAI API.
Familiarity with REST API and Soap Services
Familiarity with REST API and Soap Services
Microservices architecture, API-first approach, containerisation (Docker/Kubernetes), CI/CD pipelines * Knowledge of integration patterns, API gateways, and cloud-native deployments
Microservices architecture, API-first approach, containerisation (Docker/Kubernetes), CI/CD pipelines * Knowledge of integration patterns, API gateways, and cloud-native deployments
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Data exchange and processing skills (e.g. ETL, ESB, API...)
Data exchange and processing skills (e.g. ETL, ESB, API...)
FEATURED
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Youll work across Camunda BPMN/DMN process automation, API integration, and microservice orchestration helping their public-sector clients build secure, scalable, and resilient digital services. Profile 29 recruitment keywords: Java software engineer object-oriented design OOD Camunda BPMN DMN Spring Boot REST API microservice architecture Docker Kubernetes containerisation orchestration Git CI/CD pipelines automated testing frameworks Kafka RabbitMQ Security authentication integration patterns enterprise systems agile digital transformation automation Java developer Camunda developer Zeebe Cloud AWS Azure GCP Terraform Helm process automation agentic AI artificial intelligence security clearance SC DV eDV London home based hybrid
Youll work across Camunda BPMN/DMN process automation, API integration, and microservice orchestration helping their public-sector clients build secure, scalable, and resilient digital services. Profile 29 recruitment keywords: Java software engineer object-oriented design OOD Camunda BPMN DMN Spring Boot REST API microservice architecture Docker Kubernetes containerisation orchestration Git CI/CD pipelines automated testing frameworks Kafka RabbitMQ Security authentication integration patterns enterprise systems agile digital transformation automation Java developer Camunda developer Zeebe Cloud AWS Azure GCP Terraform Helm process automation agentic AI artificial intelligence security clearance SC DV eDV London home based hybrid
Related Jobs
Locations
- The City, City (EC4)
- Shoreditch
- Southwark
- Bellfields
- Causeway
- Covent Garden
- Datchet Common
- Euston
- Freshbrook
- Keeley Green
- City of London
- Milton Keynes
- Central London
- West End
- Reading
- South East London
- Stevenage
- East London
- Southampton
- North West London
- London
- Buckinghamshire
- Hertfordshire
- Berkshire
- Oxfordshire
- Hampshire
- Surrey
- Wiltshire
- Gloucestershire
- Bedfordshire
- South East
- South West
- Midlands
- West Midlands