49 api developer jobs found in London

Front-end Developer (8 Month Day Rate Contactor) Contract Type Day Rate Contractor Closing Date 31 August, 2026 Job Category Tech, Data and Digital Business Unit Systems and Infrastructure (UKT) Location London , United Kingdom Posted on 20 August, 2026 The opportunity  As a Front-End Developer you will be responsible for: Build, test and document applications, using an internally developed JavaScript / React based framework and associated utility classes Operate in an Agile/Scrum environment to produce high quality, clean, testable and maintainable code Lead / participate in Show and Tell sessions with Business and Technical Stakeholders Ensure knowledge transfer to the wider Front End / UI Development Team Act as the Front-End SME within the designated delivery team Operates in line with the Bank's Risk Management framework (including sub-frameworks) and relevant risk and compliance policies and procedures,...

Network Rail is at the heart of revitalising Britain's railway. From Crossrail - Europe's largest civil engineering project - to investment in world-class stations and major programmes of electrification, we are involved in some of the most ambitious and diverse ventures that this country has ever seen. We at Network Rail are dedicated to becoming one of Britain 's best employers and believe this starts with placing the candidate at the heart of everything we do!   As a  Agentic Automation Engineer , your main responsibilities will be:   We 're looking for an Agentic Automation Engineer to help shape and deliver the next generation of AI-driven automation across the rail industry. This is not a traditional Power Platform Developer role. We 're seeking someone with hands-on experience building AI agents and agentic solutions , primarily within the Microsoft Agentic AI ecosystem , leveraging low-code technologies to design, orchestrate and deploy...

Skills & Experience Job roles: Back End Experience level: Lead Core skills considered: APIs, REST, SOAP, JSON, SQL Other skills considered: Java, Groovy, CI/CD, AWS, Azure Logistics Base salary: Undisclosed Employment type: Freelance/Contract Remote working: Hybrid Visa sponsorship: Not available Job Description We are looking for a hands-on Boomi Integration Architect who can design scalable integration solutions while leading development and delivery. The role combines architecture, technical leadership, client engagement and hands-on Boomi development. Key Responsibilities Design enterprise integration solutions using the Boomi platform. Lead discovery, requirements and solution-design sessions. Build and review complex Boomi integration processes. Develop reusable APIs, components and integration frameworks....

Skills & Experience Job roles: Back End Experience level: Mid, Senior Core skills considered: APIs, REST, SOAP, SQL, Java Other skills considered: Groovy, CI/CD, AWS, Azure Logistics Base salary: Undisclosed Employment type: Freelance/Contract Remote working: Hybrid Visa sponsorship: Not available Job Description We are looking for an experienced Boomi Developer to design, build, test and support integration solutions using the Boomi Enterprise Platform. The role requires strong hands-on development skills across APIs, cloud applications, databases and enterprise systems. Key Responsibilities Develop and maintain integration processes using Boomi. Build integrations between cloud and on-premises applications. Configure Boomi connectors, maps, profiles, process properties and environment extensions. Develop REST,...

London, UK Apply CoreWeave is The Essential Cloud for AI™. Built for pioneers by pioneers, CoreWeave delivers a platform of technology, tools, and teams that enables innovators to build and scale AI with confidence. Trusted by leading AI labs, startups, and global enterprises, CoreWeave combines superior infrastructure performance with deep technical expertise to accelerate breakthroughs and turn compute into capability. Founded in 2017, CoreWeave became a publicly traded company (Nasdaq: CRWV) in March 2025. Learn more at  www.coreweave.com .   We're proud to be a Living Wage accredited Employer.   What You’ll Do: The Monolith AI Platform Engineering Team at CoreWeave  is responsible for transitioning existing client environments to Monolith AI’s next-generation platform, maintaining the high velocity needed to support a rapidly growing customer base. This team works...

Description Role Profile: AWS Connect Developer Duration: 12 Months+   Who We Are: AND Digital are a tech company focused on accelerating digital delivery and dedicated to closing the digital skills gap. We've been helping organisations build better digital products and stronger digital teams since 2014. We believe our work should always leave a legacy for the client. We do this through close relationships with our offices (or 'Clubs') so that our partners are always prioritized by a regional team close to them. This unique model has driven success for our clients and ourselves, evidenced by our remarkable organic growth since 2014. Today we number more than 1,500 people with Clubs all over the UK and Europe with plans for global expansion in the next couple of years. Join us - and help us fulfil our mission to close the world's digital skills gap.   Role Overview We are seeking an experienced AWS Connect Developer to design, develop,...

Java and Azure Developer : Contract Role London, England, United Kingdom WPP is the trusted growth partner for the world’s leading brands.  We unite cutting-edge media intelligence and data solutions, world-class creativity, next-generation production, transformative enterprise solutions and expert strategic counsel in a single company – powered by exceptional talent and our agentic marketing platform, WPP Open, to help our clients navigate change, capture opportunity and deliver transformational growth.    We work with the world's most valuable brands and have global reach across 100+ markets, with deep local expertise.   Our people are the key to our success. We're committed to fostering a culture of creativity, belonging and continuous learning, attracting and developing the brightest talent, and providing exciting career opportunities that help our people grow.    For more information,...

Principal Salesforce Engineer Location: London (Hybrid- 3 days working from onsite-Mandatory) Client Business Area: Asset Management Platform Immediate start Permanent/ Contract inside IR35/ Fixed term contract Applicants legally authorized to work in the United Kingdom without the need for visa sponsorship preferred We are looking for a Principal Salesforce Engineer to lead the design, development, and delivery of scalable, secure, and high-performing Salesforce solutions within a leading Asset Management environment. Key Responsibilities: Design and build Salesforce solutions using Apex, Lightning Web Components (LWC), Flows, and declarative tools. Develop integrations with enterprise platforms using APIs, MuleSoft, and event-driven architectures. Drive engineering best practices, including code reviews, automated testing, CI/CD, and DevOps. Collaborate with architects, business stakeholders, and delivery teams to translate complex...

Location: London 1-2 days a week. Department: Engineering Employment Type: Contract Contract Length: 6 months (with potential for extension) About YLD: Our goal is to help our clients keep moving forward. We work with them to build the skills and capabilities they need to stay ahead of the competition, and we know our success only happens when they succeed. We’re a team of curious, talented people, and we’re committed to making YLD a place where great people want to work, grow, and stay. We’re a remote-first consultancy specialising in software engineering, product design, and data. Our teams are based across London, Lisbon, and Porto, and we create digital solutions that continue to deliver value long after our work is done. About the role: As a Senior Software Engineer at YLD, you’ll be part of a client team building innovative products. We’re looking for someone curious, passionate, driven, and...

Why Keyrus, Why Now! Keyrus is an international group of 2,800 consultants and experts across 28 countries, built on a single conviction: AI does not transform businesses. Architected intelligence does. For more than 30 years, we have been building the data foundations that make intelligent systems work — designing the Operating System of the intelligent enterprise, where intelligence is embedded into the core of business processes to create sustainable value: we operationalise intelligence. AI does not replace humans. It repositions us to a place no system can follow: understanding, deciding, designing, and creating. At Keyrus, you will not just develop skills — you will develop judgment. Your expertise sharpens with every system you architect, every client challenge you solve, and every deployment that compounds on the last. Over time, you grow into one of the rarest professionals of the intelligence era: someone who bridges data, AI, and human...

Job title: AI & Automation Director Contract Type: Freelance, 3-4x days per week, 3x months - with potential to extend Location: Shoreditch, London Reporting into: Operations Director Hybrid/ Remote: WFH Monday & Friday. In the office Tuesday-Thursday ABOUT US Seen Connects is one of the UK's leading influencer and social agencies. We partner with some of the world's most recognisable brands to create campaigns that drive real business results. We're entering the next phase of our growth and are making a significant investment in AI, automation and operational excellence. Our ambition is not simply to adopt AI tools, but to continue building an AI-enabled agency that operates smarter, moves faster and scales more efficiently than our competition. We're looking for an experienced AI & Automation Director to lead that work on a freelance basis.   THE ROLE This is a senior role, helping us shape and deliver the agency's...

Job Introduction Handelsbanken combines a long-established relationship banking model with secure, resilient, and customer-focused technology. Our technology teams enable the Bank’s decentralised way of working, delivering systems built for stability, trust, and long-term value. We are on a multi-year technology and digital transformation journey to enhance customer experience and improve how colleagues work together. By modernising platforms, simplifying processes, and better connecting data and systems, we help relationship teams focus on customers and less on complexity. Our decentralised culture extends to technology. Teams are trusted to take ownership, make informed decisions, and deliver sustainable, high-quality solutions. We value engineering excellence, pragmatic problem-solving, and strong collaboration across technology, business, and risk. We offer technologists the opportunity to build lasting careers, deepen their expertise, and contribute to meaningful...

What You 'll Be Doing Lead the design and governance of end-to-end Intelligent Automation and Agentic AI solutions. Define scalable, secure and reusable architecture patterns aligned to enterprise architecture principles and technology strategy. Develop architecture standards, reference architectures and integration frameworks for industry-wide adoption. Design low-code and pro-code automation solutions using modern Microsoft and cloud-native technologies. Create reusable architecture capability products, implementation blueprints and technical design standards. Review and assure solution designs, providing architectural governance and technical leadership across delivery teams and partners. Assess emerging technologies and lead proof-of-concepts to support the adoption of innovative automation and AI capabilities. Drive architecture consistency, technical quality and long-term sustainability across the automation portfolio. Coach and mentor architects...

Python Developer (Azure / FastAPI) — £350/day — Outside IR35 — Hybrid, Central London (3 days on-site) About the role A significant opportunity to work with a leading global independent financial services firm, delivering a loan management platform that handles complex servicing workflows in a regulated environment. You'll be working to a high bar for correctness, traceability and testing — and you'll be based out of excellent offices in central London three days a week. We are looking for a mid-level Python developer to join the delivery team. This is a hands-on engineering role in a small, senior team — you'll own features end to end and you'll have direct visibility of the client and the business problems you're solving. What you'll be doing Building and maintaining Python services — FastAPI applications and Azure Functions Designing and consuming REST APIs, with an eye on validation, versioning and clear...

What You 'll Be Doing Lead the design and governance of end-to-end Intelligent Automation and Agentic AI solutions. Define scalable, secure and reusable architecture patterns aligned to enterprise architecture principles and technology strategy. Develop architecture standards, reference architectures and integration frameworks for industry-wide adoption. Design low-code and pro-code automation solutions using modern Microsoft and cloud-native technologies. Create reusable architecture capability products, implementation blueprints and technical design standards. Review and assure solution designs, providing architectural governance and technical leadership across delivery teams and partners. Assess emerging technologies and lead proof-of-concepts to support the adoption of innovative automation and AI capabilities. Drive architecture consistency, technical quality and long-term sustainability across the automation portfolio. Coach and mentor architects...

Senior Full Stack Engineer - Contract What is Flagstone? Flagstone is many things. An online savings platform, reinventing how individuals, businesses, and charities manage, protect, and grow their cash. A diverse group of people, bound by a collaborative spirit, and shared purpose. And lastly, a thriving, profitable business – where smart people do their best work. Each definition shares a common thread: our unique culture. It’s our pride and joy. And our competitive advantage. A feel for our culture: To revolutionise the savings market, we need to be at our best. But high performance takes more than talent – it takes a culture of kindness, respect, and growth. That’s why we’re building a diverse, inclusive community, where your voice is heard and valued. Where, with close support and room to develop, you can surpass even your own expectations. And be rewarded for it. We may not change the world, but we  can change the...

Senior Full Stack Data Quality Engineer Assignment type: Outside IR35   The supplier will be engaged to provide specialist hands-on data quality engineering services to the Finance & Data Reporting Product Team across TMHCC’s modern data platform testing, data quality engineering, and test automation.   The engagement is focused on delivering agreed testing and automation outcomes across defined operational assurance priorities and initiative delivery outcomes. The supplier will validate data across the full data lifecycle, including ingestion, transformation, data lake, data warehouse, reporting and BI, APIs, metadata, lineage, and reconciliation.   Assignment Tasks / Deliverables   Full Stack Data Quality Engineering: Design and execute data quality testing across ingestion, transformation, warehouse, reporting/BI, APIs, metadata, lineage, and reconciliation layers. Validate Snowflake data lake and data...

Role description Role: Generative AI Scientist Permanent / Fixed term contract/ Contract Inside IR35 Contract Length: Initial 6-12 months with possible extensions Start Date: Immediate preferred Location Requirement:Onsite (3 days per week in the office and 2 days remote ) Applicants legally authorized to work in the United Kingdom without the need for current or future visa sponsorship preferred Experience: Minimum10-15 years We are seeking a Generative AI Scientist to design and deliver agent‑based, AI‑enabled solutions integrated into complex enterprise environments. This is a hands‑on engineering role, focused on building production‑grade AI systems that move beyond experimentation into scalable, secure, and measurable outcomes for our clients. You’ll work closely with UST’s engineering teams, AI specialists, and business stakeholders to translate high‑value use cases into robust solutions. What You’ll Be Doing:...

Job description   Job Title: Full Stack Developer (contract) Location: London Hybrid. Travel to the London office on 3 days a week Duration: 11 months Contract Start Date: ASAP *note client onboarding takes 6 weeks from offer Day Rate: Competitive (Inside IR35)   Deloitte Working with the Deloitte Associate (Contractor) Programme means we can offer you the opportunity to work on a variation of industry and client related projects. Our aim is to retain the best talent and so when your project end date nears our team of Talent Community Advisors will be working with you to look at alternative projects within the firm that suit your experience should you wish to continue with Deloitte.   The Role We are looking for an experienced Full Stack Developers to work in the Technology and Transformation Team at Deloitte. You will work with one of our global financial services clients. This...

Job description   Job Title: Senior Full Stack Developer (contract) Location: London Hybrid. Travel to the London office 3 days a week Duration: 11 months Contract Start Date: ASAP *note client onboarding takes 6 weeks from offer Day Rate: Competitive (Inside IR35)   Deloitte Working with the Deloitte Associate (Contractor) Programme means we can offer you the opportunity to work on a variation of industry and client related projects. Our aim is to retain the best talent and so when your project end date nears our team of Talent Community Advisors will be working with you to look at alternative projects within the firm that suit your experience should you wish to continue with Deloitte.   The Role We are looking for Senior Full Stack Developers to work in the Technology and Transformation Team at Deloitte. You will work with one of our global financial services clients. This...