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48 Contract API jobs in Hertfordshire + 20 miles
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Senior API Technical Consultant (GraphQL Specialist)
Senior API Technical Consultant (GraphQL Specialist)
Staffworx Limited
Slough (SL1)
market rates, outside IR35, 2 days on site
Lead the designand evolution of our API schemas, ensuring they meet the complex demands of a rapidly growing platform. * Expert levelGraphQL, including advanced API design, schema evolution, performance optimisation.
Lead the designand evolution of our API schemas, ensuring they meet the complex demands of a rapidly growing platform. * Expert levelGraphQL, including advanced API design, schema evolution, performance optimisation.
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This role is ideal for someone who specialises in system integration, API design, and cloud-based architecture (Azure) and enjoys shaping strategy as well as guiding delivery teams. * Design and govern API-led integrations, interface specifications, message schemas, and data flows. * Hands-on knowledge of Microsoft Azure integration services (API Management, Service Bus, Logic Apps, Event Grid, etc.) * Strong understanding of enterprise integration patterns, API management platforms (Apigee/Azure API Mgmt)
This role is ideal for someone who specialises in system integration, API design, and cloud-based architecture (Azure) and enjoys shaping strategy as well as guiding delivery teams. * Design and govern API-led integrations, interface specifications, message schemas, and data flows. * Hands-on knowledge of Microsoft Azure integration services (API Management, Service Bus, Logic Apps, Event Grid, etc.) * Strong understanding of enterprise integration patterns, API management platforms (Apigee/Azure API Mgmt)
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Utilise Fetch API to automate interactions with web services and validate data flows.
Utilise Fetch API to automate interactions with web services and validate data flows.
FEATURED
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Expertise on Oracle Simphony, API knowledge, Knowledge of Product Limitations
Expertise on Oracle Simphony, API knowledge, Knowledge of Product Limitations
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API and SDK automation, metadata ingestion and catalogue enrichment
API and SDK automation, metadata ingestion and catalogue enrichment
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Strong knowledge of API integration.
Strong knowledge of API integration.
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Cloud Solution Architect
Cloud Solution Architect
International Business Solutions Consulting Limited
Soho, Central London (W1), W1D
£500 per day
The ideal candidate will have strong experience in delivering large-scale, fault-tolerant systems; setting SLOs/SLIs, Terraform and modern CI/CD tools (Azure DevOps, GitHub Actions, Harness, Jenkins, Spinnaker), Containers & orchestration (Kubernetes) and service mesh (eg, Istio), API design & security (REST/OpenAPI, mTLS, authN/Z), Scripting in Bash, PowerShell, or Python, Cloud Expertise (Depth in One, Ready to Cross-Train), Azure: ARM/Bicep, AKS, Application Gateway, API Management, Azure Storage, GCP: GKE, Cloud Load Balancing, Cloud Armor, Istio, Stackdriver, Jenkins, Apigee. The ideal candidate will desirably have strong experience in Harness, HashiCorp Vault, Dynatrace, Docker/buildah, NodeJS for API tooling, Relevant Azure or GCP certifications.
The ideal candidate will have strong experience in delivering large-scale, fault-tolerant systems; setting SLOs/SLIs, Terraform and modern CI/CD tools (Azure DevOps, GitHub Actions, Harness, Jenkins, Spinnaker), Containers & orchestration (Kubernetes) and service mesh (eg, Istio), API design & security (REST/OpenAPI, mTLS, authN/Z), Scripting in Bash, PowerShell, or Python, Cloud Expertise (Depth in One, Ready to Cross-Train), Azure: ARM/Bicep, AKS, Application Gateway, API Management, Azure Storage, GCP: GKE, Cloud Load Balancing, Cloud Armor, Istio, Stackdriver, Jenkins, Apigee. The ideal candidate will desirably have strong experience in Harness, HashiCorp Vault, Dynatrace, Docker/buildah, NodeJS for API tooling, Relevant Azure or GCP certifications.
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Azure Cosmos DB (SQL/Mongo API), NoSQL modelling
Azure Cosmos DB (SQL/Mongo API), NoSQL modelling
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Strong grasp of databases (SQL/NoSQL) and API integrations
Strong grasp of databases (SQL/NoSQL) and API integrations
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Knowledge of ServiceNow scripting (JavaScript, Glide API) a plus.
Knowledge of ServiceNow scripting (JavaScript, Glide API) a plus.
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We are looking for a strong Full Stack Developer to deliver a short-term project involving a static website build, API scraping, and structured JSON output. * Develop API scraping scripts to extract structured data reliably * Proven experience building API scrapers (Axios, Puppeteer, BeautifulSoup, Cheerio, or similar) * Knowledge of API rate limits and bypass methods
We are looking for a strong Full Stack Developer to deliver a short-term project involving a static website build, API scraping, and structured JSON output. * Develop API scraping scripts to extract structured data reliably * Proven experience building API scrapers (Axios, Puppeteer, BeautifulSoup, Cheerio, or similar) * Knowledge of API rate limits and bypass methods
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Full-Stack Software Developer
Full-Stack Software Developer
Sanderson Government and Defence
City of London (EC1), EC1
Up to £520 per day
REST/JSON API design
REST/JSON API design
NEWFEATURED
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Familiarity with microservices, API integration patterns and cloud concepts such as AWS.
Familiarity with microservices, API integration patterns and cloud concepts such as AWS.
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Azure Cosmos DB Admin and Developer
Azure Cosmos DB Admin and Developer
Vallum Associates Limited
The City, City of London (EC4), EC4M
£500 per hour
This role involves architecting cloud-native solutions using Azure Cosmos DB (SQL API and Mongo API), implementing effective partitioning strategies, indexing, and consistency models to support real-time financial data processing. Architect and develop cloud-native applications using Azure Cosmos DB (SQL API, Mongo API)
This role involves architecting cloud-native solutions using Azure Cosmos DB (SQL API and Mongo API), implementing effective partitioning strategies, indexing, and consistency models to support real-time financial data processing. Architect and develop cloud-native applications using Azure Cosmos DB (SQL API, Mongo API)
Strong grasp of API integrations, middleware and multi system architectures.
Strong grasp of API integrations, middleware and multi system architectures.
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Hands-on with PowerShell and Microsoft Graph API for security automation
Hands-on with PowerShell and Microsoft Graph API for security automation
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Build and maintain API-based integrations with systems such as ServiceNow, NetBox, and GitHub.
Build and maintain API-based integrations with systems such as ServiceNow, NetBox, and GitHub.
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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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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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Oracle Fusion Cloud Sr. Technical Integration Manager
Oracle Fusion Cloud Sr. Technical Integration Manager
Indotronix Avani UK Ltd
St James, South West London (SW1), SW1A
Unspecified
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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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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Senior Java Software Engineer (Urgent)
Senior Java Software Engineer (Urgent)
Morson Edge
Tower Hill, City of London (EC3), E1W 1WY
£500 - 600 per day
We are seeking an experienced Senior Java Software Engineer to join the IT team at a leading bank, supporting the delivery, maintenance, and enhancement of core systems across various business areas, including operations, compliance, transactions, and client management. This is a 6-month contract role offering an excellent day rate, ideally suited to candidates with experience in regulated environments, financial services, or government/public sector organisations. In this role, you will be an integral part of the software development lifecycle, working closely with Senior Java Developers, UI/UX teams, and Agile Transformation to architect, build, and deliver greenfield, brownfield, and integration applications. You will be expected to employ best design and development practices, solve technical challenges, and contribute to high-quality system analysis and developme
We are seeking an experienced Senior Java Software Engineer to join the IT team at a leading bank, supporting the delivery, maintenance, and enhancement of core systems across various business areas, including operations, compliance, transactions, and client management. This is a 6-month contract role offering an excellent day rate, ideally suited to candidates with experience in regulated environments, financial services, or government/public sector organisations. In this role, you will be an integral part of the software development lifecycle, working closely with Senior Java Developers, UI/UX teams, and Agile Transformation to architect, build, and deliver greenfield, brownfield, and integration applications. You will be expected to employ best design and development practices, solve technical challenges, and contribute to high-quality system analysis and developme
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Description - 1. Consumes existing messages from the AMP bus (AMPS is a product from 60East) containing Json messages. 2. Transforms and Routes messages to Dynatrace ingest endpoints. 3. Publishes metrics/dimensions via Dynatrace v2 APIs. 4. Enriches records with required Dynatrace metadata (e.g., dt.entity.host) to correctly bind data to hosts/entitiesmethod for building/maintaining the metadata mapping table to be agreed during design. Key Responsibilities * Design and implement the message consumer and router for Application to Dynatracetarget processor. * Publish metrics/dimensions to Dynatrace v2 APIs correctly and efficiently. * Create and manage metadata enrichment to bind data to hosts/entities (e.g., dt.entity.host). * Ensure security, reliability, and observability of the integration. * Collaborate with platform monitoring team and SREs for alignment and app
Description - 1. Consumes existing messages from the AMP bus (AMPS is a product from 60East) containing Json messages. 2. Transforms and Routes messages to Dynatrace ingest endpoints. 3. Publishes metrics/dimensions via Dynatrace v2 APIs. 4. Enriches records with required Dynatrace metadata (e.g., dt.entity.host) to correctly bind data to hosts/entitiesmethod for building/maintaining the metadata mapping table to be agreed during design. Key Responsibilities * Design and implement the message consumer and router for Application to Dynatracetarget processor. * Publish metrics/dimensions to Dynatrace v2 APIs correctly and efficiently. * Create and manage metadata enrichment to bind data to hosts/entities (e.g., dt.entity.host). * Ensure security, reliability, and observability of the integration. * Collaborate with platform monitoring team and SREs for alignment and app
PREMIUM
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Software Engineer (Hardware Integration with .NET)
Software Engineer (Hardware Integration with .NET)
IO Associates
City of London (EC1)
£600 - £800 per day + Outside IR35 and Hybrid
Role: Staff Software Engineer - Sector: Life Sciences - Location: London - Days Onsite: 3 per week - Day Rate: £800 Outside IR35 - Duration: 4 Months then to extend or go Permanent - iO Associates have partnered with Life Science Manufacturing company on their search for a Staff Software Engineer who has a strong background in integrating Medical Devices. This role will give you the opportunity to make a real impact in Healthcare and Life Sciences. Essential Requirements * Strong .NET / C# background * Significant experience integrating and communicating with hardware devices * Ability to handle Windows devices, drivers, and communication layers * 8+ years of experience at a staff-level, capable of working autonomously * Not a web-focused developer; needs to be fully hardware-integration oriented - Beneficial Experience * gRPC, REST APIs, HTTP * Integrating devices in
Role: Staff Software Engineer - Sector: Life Sciences - Location: London - Days Onsite: 3 per week - Day Rate: £800 Outside IR35 - Duration: 4 Months then to extend or go Permanent - iO Associates have partnered with Life Science Manufacturing company on their search for a Staff Software Engineer who has a strong background in integrating Medical Devices. This role will give you the opportunity to make a real impact in Healthcare and Life Sciences. Essential Requirements * Strong .NET / C# background * Significant experience integrating and communicating with hardware devices * Ability to handle Windows devices, drivers, and communication layers * 8+ years of experience at a staff-level, capable of working autonomously * Not a web-focused developer; needs to be fully hardware-integration oriented - Beneficial Experience * gRPC, REST APIs, HTTP * Integrating devices in
FEATURED
Urgent 12-month Hybrid AI/Machine Learning (ML) engineer role paying £400 a day inside IR35 in central London with 2-3 days in the office a week. Start before Christmas, I need to send candidates today for this to be possible. Interviews next week apply asap/Today - Build and optimize AI/ML pipelines for predictive modelling, NLP, and generative AI applications. Perform Exploratory Data Analysis (EDA), data mining, and visualization to extract insights. Design and implement Big Data solutions using Hadoop, Spark, PySpark, and Data Lake architectures. Develop and deploy ML models (supervised, unsupervised, tree-based, ensemble methods). Implement deep learning architectures (CNN, RNN, LSTM) using TensorFlow, PyTorch, and Keras. Work on NLP and Generative AI tasks including embeddings, transformers (BERT, GPT), and OpenAI APIs.
Urgent 12-month Hybrid AI/Machine Learning (ML) engineer role paying £400 a day inside IR35 in central London with 2-3 days in the office a week. Start before Christmas, I need to send candidates today for this to be possible. Interviews next week apply asap/Today - Build and optimize AI/ML pipelines for predictive modelling, NLP, and generative AI applications. Perform Exploratory Data Analysis (EDA), data mining, and visualization to extract insights. Design and implement Big Data solutions using Hadoop, Spark, PySpark, and Data Lake architectures. Develop and deploy ML models (supervised, unsupervised, tree-based, ensemble methods). Implement deep learning architectures (CNN, RNN, LSTM) using TensorFlow, PyTorch, and Keras. Work on NLP and Generative AI tasks including embeddings, transformers (BERT, GPT), and OpenAI APIs.