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        The City, City (EC4)
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        45 Contract API jobs in Harmondsworth + 20 miles

        Full Stack Engineer TypeScript API React

        Client Server
        Shoreditch, East London (E1), EC2A
        £50000 - £60000 per annum + benefits
        Full Stack Engineer / Developer (TypeScript API React) London / WFH to £60k - Apply now to find out more about this Full Stack Engineer / Developer (TypeScript API React) opportunity.
        Full Stack Engineer / Developer (TypeScript API React) London / WFH to £60k - Apply now to find out more about this Full Stack Engineer / Developer (TypeScript API React) opportunity.
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        PREMIUM
        You will use your expertise in C#/.NET and modern APIs (REST, WebAPI, JSON, OAuth2) to build fault-tolerant, event-driven integrations, support customers and partners with API usage, and deliver clear, high-quality documentation while maintaining security, GDPR compliance, and operational reliability. Taking integration leadership, you will design and maintain well-documented financial and third-party integrations built on modern API standards. * Support customers and partners with integration setup and API usage
        You will use your expertise in C#/.NET and modern APIs (REST, WebAPI, JSON, OAuth2) to build fault-tolerant, event-driven integrations, support customers and partners with API usage, and deliver clear, high-quality documentation while maintaining security, GDPR compliance, and operational reliability. Taking integration leadership, you will design and maintain well-documented financial and third-party integrations built on modern API standards. * Support customers and partners with integration setup and API usage
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        Front End Engineer

        InfinityQuest Ltd,
        Harmondsworth, West Drayton (UB7)
        Unspecified
        Strong knowledge of API integration.
        Strong knowledge of API integration.
        NEW

        TM Forum SOM Architect

        Stackstudio Digital Ltd.
        Windsor (SL4)
        From £425 to £450 per day
        Act as the champion for TMF ODA and Open API principles across Energy Services Platform. Strong experience designing and implementing solutions using TM Forum Open APIs and a deep understanding of the ODA and Open API frameworks - Proficiency in RESTful API design, JSON, OpenAPI/Swagger specifications, microservices architecture, and cloud-native deployment models (Docker, Kubernetes, public/hybrid cloud platforms)
        Act as the champion for TMF ODA and Open API principles across Energy Services Platform. Strong experience designing and implementing solutions using TM Forum Open APIs and a deep understanding of the ODA and Open API frameworks - Proficiency in RESTful API design, JSON, OpenAPI/Swagger specifications, microservices architecture, and cloud-native deployment models (Docker, Kubernetes, public/hybrid cloud platforms)
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        Role - .Net Engineer - Location - Hybrid, Home and twice a month onsite (multiple locations) Contract - Initial 3 months, high probability of extension to 2027 - Rate - £475 to £525 per day - Start - ASAP - This role has been deemed Inside IR35. You must hold active SC Clearance to be eligible for this role. The Opportunity - We are working in partnership with a leading defence systems integrator to recruit a .Net Engineer for a major long-term programme of work. This is an exciting opportunity to join a highly capable engineering team delivering innovative software solutions across complex and mission-critical environments. If you’re looking to broaden your technical exposure; particularly across modern data platforms and integration technologies—this role offers the chance to grow within a dynamic, fast-moving setting where no two challenges are the same. The Role
        Role - .Net Engineer - Location - Hybrid, Home and twice a month onsite (multiple locations) Contract - Initial 3 months, high probability of extension to 2027 - Rate - £475 to £525 per day - Start - ASAP - This role has been deemed Inside IR35. You must hold active SC Clearance to be eligible for this role. The Opportunity - We are working in partnership with a leading defence systems integrator to recruit a .Net Engineer for a major long-term programme of work. This is an exciting opportunity to join a highly capable engineering team delivering innovative software solutions across complex and mission-critical environments. If you’re looking to broaden your technical exposure; particularly across modern data platforms and integration technologies—this role offers the chance to grow within a dynamic, fast-moving setting where no two challenges are the same. The Role
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        NEW

        Full Stack Developer

        Loopla
        Euston, North West London (NW1), NW1 2RT
        Competitive
        Vitest/Jest, Docker, CI/CD (GitHub Actions), Shadcn/MUI, MongoDB, microservices, Cloudflare/CDNs, Firebase, Google Maps API, startup experience.
        Vitest/Jest, Docker, CI/CD (GitHub Actions), Shadcn/MUI, MongoDB, microservices, Cloudflare/CDNs, Firebase, Google Maps API, startup experience.
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        Associate Engineering Manager - Salesforce

        The Stepstone Group
        Southwark, South East London (SE1), SE1 0TA
        Competitive salary
        Occasionally, being able to lend hands-on support to the team working on and using the following technologies: Salesforce (APEX classes, metadata API, etc.) and Salesforce CLI (SFDX), Visual Studio Code, Git, CI/CD, AWS * Technical knowledge and understanding of Salesforce (APEX classes, metadata API, etc.) and Salesforce CLI (SFDX); Sales cloud essential,?marketing cloud desirable, CPQ cloud?desirable,?
        Occasionally, being able to lend hands-on support to the team working on and using the following technologies: Salesforce (APEX classes, metadata API, etc.) and Salesforce CLI (SFDX), Visual Studio Code, Git, CI/CD, AWS * Technical knowledge and understanding of Salesforce (APEX classes, metadata API, etc.) and Salesforce CLI (SFDX); Sales cloud essential,?marketing cloud desirable, CPQ cloud?desirable,?
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        NEWPREMIUM

        Technical Business Analyst

        Aqovia UK Limited
        Central London (W1)
        From £60,000 to £80,000 per annum
        As a Technical Business Analyst you will be working on our consulting projects, primarily designing RESTful API services. * Capture and curate business requirements and system documentation in JIRA/Confluence, user stories, API design, API enhancements * Design RESTful web APIs for new and existing products in an API first context, in accordance with strategic guidance provided by the technical architect. Specify contracts for messaging and web services, primarily using JSON Schema and Open API Specification (Swagger), respectively. * Comfortable working with source code (Git) to manage API specifications. * Able to work with a web API testing tool such as Postman, including crafting authentication tokens
        As a Technical Business Analyst you will be working on our consulting projects, primarily designing RESTful API services. * Capture and curate business requirements and system documentation in JIRA/Confluence, user stories, API design, API enhancements * Design RESTful web APIs for new and existing products in an API first context, in accordance with strategic guidance provided by the technical architect. Specify contracts for messaging and web services, primarily using JSON Schema and Open API Specification (Swagger), respectively. * Comfortable working with source code (Git) to manage API specifications. * Able to work with a web API testing tool such as Postman, including crafting authentication tokens
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        Business Analyst

        REC SOLUTIONS LIMITED
        The City, City of London (EC4), EC4N
        Competitive base salary plus bonus and benefits
        Proficiency in creating and maintaining clear, comprehensive technical documentation and API specifications.
        Proficiency in creating and maintaining clear, comprehensive technical documentation and API specifications.
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        NEW

        Salesforce Tech Lead

        Stackstudio Digital Ltd.
        Windsor (SL4)
        From £450 to £475 per day
        Job Title:Salesforce Tech Lead - Location:Windsor, UK (1 day a week) Job Purpose and Primary Objectives:Salesforce Tech Lead - Key Responsibilities (Please specify if the position is an individual one or part of a team) * Participate in refining and scoping upcoming sprint work. * Assist solution architects with technical design and breaking down complex tasks. * Accountable for timely delivery of assigned tickets, meeting acceptance criteria. * Conduct spikes/investigations into innovative technologies for future project viability. * Ensure teammates' work meets code quality standards through reviews. * Coordinate with other teams for integrations, ensuring alignment of tasks and APIs. * Work with the QA team to investigate and resolve issues. * Mentor junior team members, providing assistance with tasks and problem-solving.
        Job Title:Salesforce Tech Lead - Location:Windsor, UK (1 day a week) Job Purpose and Primary Objectives:Salesforce Tech Lead - Key Responsibilities (Please specify if the position is an individual one or part of a team) * Participate in refining and scoping upcoming sprint work. * Assist solution architects with technical design and breaking down complex tasks. * Accountable for timely delivery of assigned tickets, meeting acceptance criteria. * Conduct spikes/investigations into innovative technologies for future project viability. * Ensure teammates' work meets code quality standards through reviews. * Coordinate with other teams for integrations, ensuring alignment of tasks and APIs. * Work with the QA team to investigate and resolve issues. * Mentor junior team members, providing assistance with tasks and problem-solving.
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        Salesforce Tech Lead

        Infoplus Technologies UK Ltd
        Windsor, Berkshire
        From £450 to £500 per day
        Windsor, UK - Will the role be 100% remote, Hybrid or 100% office? (Mandatory) Hybrid (visit to office once every week) to begin with - Is BGC required to completed before joining?(Y/N) * Participate in refining and scoping upcoming sprint work. * Assist solution architects with technical design and breaking down complex tasks. * Accountable for timely delivery of assigned tickets, meeting acceptance criteria. * Conduct spikes/investigations into innovative technologies for future project viability. * Ensure teammates' work meets code quality standards through reviews. * Coordinate with other teams for integrations, ensuring alignment of tasks and APIs. * Work with the QA team to investigate and resolve issues. * Mentor junior team members, providing assistance with tasks and problem-solving. * At least 5+ years Salesforce, both declarative and programmatic * Sales an
        Windsor, UK - Will the role be 100% remote, Hybrid or 100% office? (Mandatory) Hybrid (visit to office once every week) to begin with - Is BGC required to completed before joining?(Y/N) * Participate in refining and scoping upcoming sprint work. * Assist solution architects with technical design and breaking down complex tasks. * Accountable for timely delivery of assigned tickets, meeting acceptance criteria. * Conduct spikes/investigations into innovative technologies for future project viability. * Ensure teammates' work meets code quality standards through reviews. * Coordinate with other teams for integrations, ensuring alignment of tasks and APIs. * Work with the QA team to investigate and resolve issues. * Mentor junior team members, providing assistance with tasks and problem-solving. * At least 5+ years Salesforce, both declarative and programmatic * Sales an
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        API Development & Integration - Proficient in designing and building RESTful APIs using FastAPI, Flask, or Django REST Framework for exposing AI models and automation services. Experience with API authentication (OAuth, JWT), rate limiting, error handling, API documentation (Swagger/OpenAPI), webhooks, and integrating disparate systems to create seamless automated workflows. Ability to assess when RPA vs. API integration vs. AI solutions are most appropriate, and experience building hybrid automation solutions combining multiple technologies.
        API Development & Integration - Proficient in designing and building RESTful APIs using FastAPI, Flask, or Django REST Framework for exposing AI models and automation services. Experience with API authentication (OAuth, JWT), rate limiting, error handling, API documentation (Swagger/OpenAPI), webhooks, and integrating disparate systems to create seamless automated workflows. Ability to assess when RPA vs. API integration vs. AI solutions are most appropriate, and experience building hybrid automation solutions combining multiple technologies.
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        NEW
        Fusion Cloud Products: Deep knowledge of Oracle Integration Cloud and other relevant integration requirements e.g., XSLT transformations, API security, interface error handling with practical design, configuration, and testing experience.
        Fusion Cloud Products: Deep knowledge of Oracle Integration Cloud and other relevant integration requirements e.g., XSLT transformations, API security, interface error handling with practical design, configuration, and testing experience.
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        Software Engineering Lead Java AI - FinTech

        Client Server
        Shoreditch, East London (E1), EC2A
        £120000 - £140000 per annum + bonus + benefits
        Software Engineering Lead (Java AI) London / WFH to £140k - Are you a technical leader with a strong knowledge of AI and its practical uses within software engineering? You could be progressing your career in a senior, hands-on Engineering Manager role at a global FinTech / CFD trading company that has been consistently voted as one of the UKs top employers. As a Software Engineering Lead you'll head up a team of nine Software Engineers whilst remaining hands-on with coding. Your primary focus will be on using Claude code (and other AI tools and frameworks) throughout the development lifecycle from initial requirements shaping through to deployment to improve speed and efficiency of software development and release. This is an influential role where you and your team will work across product engineering teams to showcase processes and procedures with AI without cuttin
        Software Engineering Lead (Java AI) London / WFH to £140k - Are you a technical leader with a strong knowledge of AI and its practical uses within software engineering? You could be progressing your career in a senior, hands-on Engineering Manager role at a global FinTech / CFD trading company that has been consistently voted as one of the UKs top employers. As a Software Engineering Lead you'll head up a team of nine Software Engineers whilst remaining hands-on with coding. Your primary focus will be on using Claude code (and other AI tools and frameworks) throughout the development lifecycle from initial requirements shaping through to deployment to improve speed and efficiency of software development and release. This is an influential role where you and your team will work across product engineering teams to showcase processes and procedures with AI without cuttin
        more
        NEWPREMIUM
        Maintain a strong understanding of offensive and defensive practices, with particular focus on web, API, bot, DDoS, and AI-related threats * Strong grasp of common web, cloud, and API protocols and their associated attack surfaces (e.g., HTTP/S, REST, OAuth, DNS, TLS, etc.)
        Maintain a strong understanding of offensive and defensive practices, with particular focus on web, API, bot, DDoS, and AI-related threats * Strong grasp of common web, cloud, and API protocols and their associated attack surfaces (e.g., HTTP/S, REST, OAuth, DNS, TLS, etc.)
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        MS Power Platform Developer with AI Chatbot - Location: Esher (two days WFH) Salary: c.£50K - £60K - This person will contribute directly to the organisations digital transformation roadmap by embedding automation and AI into our operations and business. This will involve building AI-powered conversational agents and automating business processes using Microsoft Power Platform tools like Power Apps, Power Automate, and Power Virtual Agents (part of Microsoft Copilot Studio). * Chatbot Development: Design, build, and implement AI chatbots using Power Virtual Agents/Copilot Studio to streamline interactions and automate tasks. * Process Automation: Create automated workflows and processes using Power Automate to improve efficiency and reduce manual tasks, often incorporating AI capabilities. * Application Development: Develop intelligent business applications with Power
        MS Power Platform Developer with AI Chatbot - Location: Esher (two days WFH) Salary: c.£50K - £60K - This person will contribute directly to the organisations digital transformation roadmap by embedding automation and AI into our operations and business. This will involve building AI-powered conversational agents and automating business processes using Microsoft Power Platform tools like Power Apps, Power Automate, and Power Virtual Agents (part of Microsoft Copilot Studio). * Chatbot Development: Design, build, and implement AI chatbots using Power Virtual Agents/Copilot Studio to streamline interactions and automate tasks. * Process Automation: Create automated workflows and processes using Power Automate to improve efficiency and reduce manual tasks, often incorporating AI capabilities. * Application Development: Develop intelligent business applications with Power
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        Frequently Asked Questions

        How many contract API jobs are there in Harmondsworth?
        There are 45 contract API jobs within 20 miles of Harmondsworth available on CWJobs right now.

        Where in Harmondsworth are these contract jobs?
        You can find contract jobs in The City, City (EC4), Shoreditch, Hinxton.

        What other similar jobs are there to contract API jobs in Harmondsworth?
        As well as contract API jobs in Harmondsworth, you can find contract IT, Software Development, Infrastructure, amongst many others.