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Backend Engineer Api in London

72 active opportunities · Updated October 2026

Explore current backend engineer api jobs in London. Filter by work mode, employment type, experience, department, date posted and distance.

PE
📍 London, United Kingdom· Full-time· Hybrid
✓ Quality checked

A World-Changing Company Palantir builds the world’s leading software for data-driven decisions and operations. By bringing the right data to the people who need it, our platforms empower our partners to develop lifesaving drugs, forecast supply chain disruptions, locate missing children, and more. The Role Backend Software Engineers at Palantir build software at scale to transform how organizations use data. Our Software Engineers are involved throughout the product lifecycle, from idea generation, design, prototyping, and production delivery. You will collaborate closely with technical and non-technical teammates to understand our customers' problems and build products that solve them. We encourage movement across teams to share context, skills, and experience, so you'll learn about many different technologies and aspects of each product. Engineers work autonomously and make decisions independently, within a community that will support and challenge you as you grow and develop, becoming a strong technical contributor and engineering leader. Our Product Development organization is made up of small teams of Software Engineers. Each team focuses on a specific aspect of a product. Our infrastructure teams are responsible for the lowest layers of our software stack, often focused on database technologies, distributed systems, large scale data systems, security, and application infrastructure. As a Software Engineer on infrastructure, you'll contribute high-quality code to underpin Palantir Foundry and Gotham with performant, secure, and scalable building blocks, enabling products deployed to the most important institutions in the public and private sector. You'll build the foundational capabilities that power our products used by research scientists, aerospace engineers, intelligence analysts, and economic forecasters, in countries around the world. We’re hiring engineers who are passionate about solving real-world problems and empowering both developers and

PE
📍 London, United Kingdom· Full-time· Hybrid
✓ Quality checked

A World-Changing Company Palantir builds the world’s leading software for data-driven decisions and operations. By bringing the right data to the people who need it, our platforms empower our partners to develop lifesaving drugs, forecast supply chain disruptions, locate missing children, and more. The Role Software Engineers at Palantir build software at scale to transform how organizations use data. Our Software Engineers are involved throughout the product lifecycle, from idea generation, design, prototyping, and production delivery. You will collaborate closely with technical and non-technical teammates to understand our customers' problems and build products that solve them. We encourage movement across teams to share context, skills, and experience, so you'll learn about many different technologies and aspects of each product. Engineers work autonomously and make decisions independently, within a community that will support and challenge you as you grow and develop, becoming a strong technical contributor and engineering leader. Our Product Development organization is made up of small teams of Software Engineers. Each team focuses on a specific aspect of a product. Our infrastructure teams are responsible for the lowest layers of our software stack, often focused on database technologies, distributed systems, large scale data systems, security, and application infrastructure. As a Software Engineer on infrastructure working on our Foundry platform, you'll contribute high-quality code to underpin Palantir Foundry and Gotham with performant, secure, and scalable building blocks, enabling products deployed to the most important institutions in the public and private sector. You'll build the foundational capabilities that power our products used by research scientists, aerospace engineers, intelligence analysts, and economic forecasters, in countries around the world. We’re hiring engineers who are passionate about solving real-world problems and empowerin

S
📍 London, England, United Kingdom
✓ High-confidence listing
Quick readStrong listing-quality and freshness signals

At Speechmatics, we’re expanding our user platform offering. We're looking for a Senior Front-End Software Engineer with a strong product mindset to help drive that growth. This is an opportunity to own end-to-end feature development at a leading-edge AI company, from shaping the user experience through to shipping and iterating based on real user feedback and analytics data. What you'll do Own product features from ideation through to delivery, contributing to UX thinking, frontend execution, and post-launch iteration Build polished, accessible user interfaces using React, JavaScript, HTML, and CSS Make UX and UI decisions independently, collaborating closely with designers and PMs rather than waiting on detailed handoffs Design and run A/B tests to validate product decisions and surface insights that improve the user experience Use analytics tooling such as Mixpanel to understand how people interact with the product and feed that learning back into what gets built Partner with backend engineers, product managers, and designers to ship features that genuinely move the needle for users and the business Write and maintain robust UI tests, taking ownership of quality in production and at scale Run user interviews and meet customers to understand how people use the product and what drives adoption What you'll need Proficiency in React, JavaScript, HTML, and CSS with a track record of shipping production-quality frontend code A product-minded engineering approach Comfort owning UX and UI decisions independently Hands-on experience with iterative development practices, including A/B testing and feature experimentation Familiarity with user analytics tools such as Mixpanel or a comparable platform Experience with UI testing frameworks and a solid grounding in frontend engineering best practices Confidence collaborating cross-functionally with designers, PMs, and backend engineers A track record of using user feedback and data to improve features Nice to have Experience us

JavaScriptReactMachine LearningAI
C
📍 London, London, United Kingdom· Full-time
✓ Quality checkedCompany trend -100%

Who are we? Cohere is the leading security-first enterprise AI company. We build cutting-edge foundation AI models and end-to-end products that are designed to solve real-world business problems. We’re training and deploying frontier models for enterprises who are building AI systems. We believe that our work is instrumental to the widespread adoption of AI and we are looking for folks that want to be part of that. We obsess over what we build. Each one of us is responsible for contributing to increasing the capabilities of our models and the value they drive for our customers. Cohere is a team of researchers, engineers, designers, and more, who are all passionate about their craft. We are a global technology company headquartered in Toronto with key offices in London, New York City, San Francisco, Montreal, Paris, Berlin and Seoul. Join us! Why this role? North is Cohere's cutting-edge AI workspace platform, designed to revolutionize the way enterprises utilize AI. It offers a secure and customizable environment, allowing companies to deploy AI while maintaining control over sensitive data. North integrates seamlessly with existing workflows, providing a trusted platform that connects AI agents with workplace tools and applications. The Agents & Automations team builds the platform inside North that lets customers create AI-powered workflows. Some of these workflows are structured automations, such as routing requests, keeping systems up-to-date, or triggering approvals. Others are more flexible agents that can gather context, use tools, make decisions, and take action across enterprise systems. As an engineer on this team, you will help build the core platform that makes this possible: the workflow builder, execution engine, integrations, debugging tools, observability, evaluation systems, and feedback loops that help customers understand and improve what they deploy. This is broad product engineering work across frontend, backend, and AI-powered systems. The

TypeScriptPythonReactKubernetes
C
📍 London, London, United Kingdom· Full-time
✓ Quality checkedCompany trend -100%

Who are we? Cohere is the leading security-first enterprise AI company. We build cutting-edge foundation AI models and end-to-end products that are designed to solve real-world business problems. We’re training and deploying frontier models for enterprises who are building AI systems. We believe that our work is instrumental to the widespread adoption of AI and we are looking for folks that want to be part of that. We obsess over what we build. Each one of us is responsible for contributing to increasing the capabilities of our models and the value they drive for our customers. Cohere is a team of researchers, engineers, designers, and more, who are all passionate about their craft. We are a global technology company headquartered in Toronto with key offices in London, New York City, San Francisco, Montreal, Paris, Berlin and Seoul. Join us! Why this role? North is Cohere's cutting-edge AI workspace platform, designed to revolutionize the way enterprises utilize AI. It offers a secure and customizable environment, allowing companies to deploy AI while maintaining control over sensitive data. North integrates seamlessly with existing workflows, providing a trusted platform that connects AI agents with workplace tools and applications. The Agents & Automations team builds the platform inside North that lets customers create AI-powered workflows. Some of these workflows are structured automations, such as routing requests, keeping systems up-to-date, or triggering approvals. Others are more flexible agents that can gather context, use tools, make decisions, and take action across enterprise systems. As an engineer on this team, you will help build the core platform that makes this possible: the workflow builder, execution engine, integrations, debugging tools, observability, evaluation systems, and feedback loops that help customers understand and improve what they deploy. This is broad product engineering work across frontend, backend, and AI-powered systems. The

TypeScriptPythonReactKubernetes
PE
📍 London, United Kingdom· Full-time· Hybrid
✓ Quality checked

A World-Changing Company Palantir builds the world’s leading software for data-driven decisions and operations. By bringing the right data to the people who need it, our platforms empower our partners to develop lifesaving drugs, forecast supply chain disruptions, locate missing children, and more. The Role Software Engineers at Palantir drive large-scale transformation through data, AI and world-leading infrastructure that supports mission-critical workloads. As an engineer within Palantir's Infrastructure teams, you'll have the opportunity to grow more quickly than you ever imagined as you contribute high-quality code directly to: The shared infrastructure underpinning Palantir Foundry, Palantir Gotham and Palantir Apollo — platforms deployed at the most important institutions across the public and private sectors Rubix and Mission Manager, our new internal-infrastructure business line, used by advanced civil and defence agencies worldwide to power their infrastructure in highly sensitive environments The substrate on which Palantir deploys Foundry and Gotham, powering workflows for research scientists, aerospace engineers, intelligence analysts and economic forecasters This means driving investments that improve the velocity and quality of our engineering. Infrastructure at Palantir spans our Foundations, Production Infrastructure and Foundry teams. Teams within Palantir's Foundations organisation are made up of a small number of engineers, each focused on one of four major categories of our infrastructure: Backend Infrastructure Developer Infrastructure Frontend Infrastructure Storage Infrastructure Production Infrastructure organisation, made up of small teams of engineers working on: Environment Platform: a Kubernetes-based PaaS spanning hundreds of production clusters Apollo: secure, fleet-wide deployment and change-management for complex microservice suites Signals: our full suite of observability and alerting tools Foundry itself is also a developer

KubernetesAIGo
PE
📍 London, United Kingdom· Full-time
✓ Quality checked

A World-Changing Company Palantir builds the world’s leading software for data-driven decisions and operations. By bringing the right data to the people who need it, our platforms empower our partners to develop lifesaving drugs, forecast supply chain disruptions, locate missing children, and more. The Role Software Engineers at Palantir drive large-scale transformation through data, AI and world-leading infrastructure that supports mission-critical workloads. As an engineer within Palantir's Infrastructure teams, you'll have the opportunity to grow more quickly than you ever imagined as you contribute high-quality code directly to: The shared infrastructure underpinning Palantir Foundry, Palantir Gotham and Palantir Apollo — platforms deployed at the most important institutions across the public and private sectors Rubix and Mission Manager, our new internal-infrastructure business line, used by advanced civil and defence agencies worldwide to power their infrastructure in highly sensitive environments The substrate on which Palantir deploys Foundry and Gotham, powering workflows for research scientists, aerospace engineers, intelligence analysts and economic forecasters This means driving investments that improve the velocity and quality of our engineering. Infrastructure at Palantir spans our Foundations, Production Infrastructure and Foundry teams. Teams within Palantir's Foundations organisation are made up of a small number of engineers, each focused on one of four major categories of our infrastructure: Backend Infrastructure Developer Infrastructure Frontend Infrastructure Storage Infrastructure Production Infrastructure organisation, made up of small teams of engineers working on: Environment Platform: a Kubernetes-based PaaS spanning hundreds of production clusters Apollo: secure, fleet-wide deployment and change-management for complex microservice suites Signals: our full suite of observability and alerting tools Foundry itself is also a developer

KubernetesAIGo
O
📍 London, Greater London, United Kingdom· Full-time
✓ Quality checkedCompany trend -100%

About the Team The Privacy Engineering team builds secure, reliable systems that help OpenAI meet its legal obligations while protecting user data. We partner closely with Legal and engineering teams across OpenAI to support lawful data access requests and other critical legal workflows. Our work turns complex, high-stakes processes into auditable and dependable technical systems with clear human oversight and strong privacy and security controls. About the Role We’re looking for a full-stack Software Engineer to build the internal tools and data pipelines that power lawful data access request workflows and Legal Operations. You will work across product and data systems to make authorized retrieval and case handling accurate, efficient, and auditable. This role is well suited to someone who enjoys translating ambiguous operational requirements into durable systems, cares deeply about sensitive-data handling, and wants to improve both technical reliability and the day-to-day experience of the people operating these workflows. In this role, you will: Design, build, and operate backend systems and workflow tooling for the full lifecycle of lawful data access requests, from intake and scoping through authorized retrieval, review, preparation, and audit. Build reliable data pipelines and interfaces across products and data stores so authorized teams can locate and handle the right records accurately and reproducibly. Implement least-privilege access, approval gates, provenance, audit trails, data minimization, and safe failure modes for sensitive workflows. Partner with Legal and Legal Operations to translate legal and operational requirements into clear technical designs and intuitive operator experiences. Identify responsible automation opportunities that reduce repetitive work while preserving human review, judgment, and accountability. Own production systems through testing, observability, incident response, documentation, and continuous reliability improvements. Hel

AWSRestAIRust
S
📍 London, England, United Kingdom· Full-time
✓ High-confidence listing

£107K – £262K/yr

Quick readStrong listing-quality and freshness signals

SpaceXAI’s mission is to create AI systems that can accurately understand the universe and aid humanity in its pursuit of knowledge. Our team is small, highly motivated, and focused on engineering excellence. This organization is for individuals who appreciate challenging themselves and thrive on curiosity. We operate with a flat organizational structure. All employees are expected to be hands-on and to contribute directly to the company’s mission. Leadership is given to those who show initiative and consistently deliver excellence. Work ethic and strong prioritization skills are important. All employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: We're seeking an exceptional Android engineer to join a small, high-impact team dedicated to creating the world's most valuable AI application, judged by the impact it delivers to users. You'll shape cutting-edge mobile experiences, blending technical mastery with a keen product sense to deliver brilliance that resonates with users. You will work on the most critical product or technical challenge at any given time. BASIC QUALIFICATIONS: Proficient in Kotlin, Jetpack Compose and reactive programming. Has a strong product sense and high craft bar. Builds intuitive and delightful user experiences. Experienced in architecting modern large production apps while embodying technical excellence. Strong sense of ownership and agency. Able to put on multiple hats and take responsibility for large areas. Able to optimize for performance, stability and reliability. PREFERRED SKILLS AND EXPERIENCE: A proven track record of shipping standout apps or features that demonstrate both technical excellence and exceptional product intuition. Deep expertise in the Android ecosystem and related development tools (Android Studio, Gradle, etc.). Rust for working with our backend components. COMPENSATION AND BENEFITS: £107,000 - £262,0

ReactAIKotlinRust
S
Licensed UK sponsor. This company appears in the UK worker sponsor register. A license does not mean this role offers sponsorship.
📍 London, United Kingdom· Full-time
✓ Quality checkedCompany trend -100%

Synthesia is the world’s leading AI video platform for business, used by over 90% of the Fortune 100. Founded in 2017, the company is headquartered in London, with offices and teams across Europe and the US. As AI continues to shape the way we live and work, Synthesia develops products to enhance visual communication and enterprise skill development, helping people work better and stay at the center of successful organizations. Following our recent Series E funding round, where we raised $200 million, our valuation stands at $4 billion. Our total funding exceeds $530 million from premier investors including Accel, NVentures (Nvidia's VC arm), Kleiner Perkins, GV, and Evantic Capital, alongside the founders and operators of Stripe, Datadog, Miro, and Webflow. We’re looking for an Engineer to join the ML Platform team at Synthesia. Our team builds and operates the systems that allow researchers and product teams to train, serve, and deploy generative models reliably and efficiently . This includes research infrastructure, production serving systems, internal tooling, and the platform interfaces that connect them. A growing part of our mission is making these systems more automation-friendly and agent-oriented , so that workflows can increasingly be operated through reliable tooling rather than manual effort. We’re looking for a strong generalist with a systems mindset: someone who is comfortable working across infrastructure, backend systems, and tooling, and who has seen ML systems in practice. this is not a pure ML Engineer role. We’re especially interested in people who think deeply about reliability, scalability, performance, and resource efficiency in complex production environments. This is a hands-on IC role with significant ownership. You’ll help shape how our ML platform evolves as we scale the number of models, workloads, tools and teams relying on it. What you’ll do Design and improve the platform systems that support model training, evaluation, and product

PythonKubernetesGitLinux
S
📍 London, England, United Kingdom· Full-time
✓ High-confidence listing
Quick readStrong listing-quality and freshness signals

We're looking for an ML Data & Platform Engineer to own the infrastructure that powers our speech AI models: the pipelines that source and prepare training data, and the platform that trains, evaluates, and serves them in production. Speech AI has a data problem most ML teams don't, and you'll be at the centre of solving it, working as part of our ML team to remove friction across the entire lifecycle and get better models into production faster. This is a broad, cross-functional role suited to someone who enjoys working across the full stack: data infrastructure, distributed systems, and production ML, and who takes ownership of problems end to end rather than waiting to be told what to fix. What you'll do Designing, building, and maintaining scalable data pipelines for ingesting, transforming, validating, and storing large datasets used to train our models Developing and maintaining web scraping and data acquisition solutions to keep training datasets fresh, high-quality, and available at scale Building and operating the infrastructure that lets the ML team deploy and evaluate new models quickly, and that serves models efficiently and reliably in production Optimising infrastructure for both iteration speed and production reliability, including GPU utilisation, job scheduling, and training efficiency Implementing observability (monitoring, logging, alerting) across data pipelines and ML systems to catch issues early and keep things running smoothly Troubleshooting complex issues across distributed systems, spanning data infrastructure, training, and inference Continuously improving our data and MLOps practices, and helping shape the roadmap for how our platform evolves as we scale What you'll need Strong proficiency in Python and SQL, with a solid backend or data engineering foundation Hands-on experience with containerisation and orchestration (Docker, Kubernetes), and working with a major cloud provider Experience building data pipelines and ETL/ELT processe

PythonSQLDockerKubernetes
S
Licensed UK sponsor. This company appears in the UK worker sponsor register. A license does not mean this role offers sponsorship.
📍 London, United Kingdom· Full-time
✓ Quality checkedCompany trend -100%

Synthesia is the world’s leading AI video platform for business, used by over 90% of the Fortune 100. Founded in 2017, the company is headquartered in London, with offices and teams across Europe and the US. As AI continues to shape the way we live and work, Synthesia develops products to enhance visual communication and enterprise skill development, helping people work better and stay at the center of successful organizations. Following our recent Series E funding round, where we raised $200 million, our valuation stands at $4 billion. Our total funding exceeds $530 million from premier investors including Accel, NVentures (Nvidia's VC arm), Kleiner Perkins, GV, and Evantic Capital, alongside the founders and operators of Stripe, Datadog, Miro, and Webflow. We’re looking for a Principal Engineer to join the ML Platform team at Synthesia. Our team builds and operates the systems that allow researchers and product teams to train, serve, and deploy generative models reliably and efficiently . This includes research infrastructure, production serving systems, internal tooling, and the platform interfaces that connect them. A growing part of our mission is making these systems more automation-friendly and agent-oriented , so that workflows can increasingly be operated through reliable tooling rather than manual effort. We’re looking for a strong generalist with a systems mindset: someone who is comfortable working across infrastructure, backend systems, and tooling, and who has seen ML systems in practice. this is not a pure ML Engineer role. We’re especially interested in people who think deeply about reliability, scalability, performance, and resource efficiency in complex production environments. This is a hands-on IC role with significant ownership. You’ll help shape how our ML platform evolves as we scale the number of models, workloads, tools and teams relying on it. What you’ll do Design and improve the platform systems that support model training, evaluation, an

PythonKubernetesGitLinux
W
📍 London, England, United Kingdom· Full-time· Remote
✓ High-confidence listingCompany trend -10%
Quick readStrong listing-quality and freshness signals

🚀 About WRITER WRITER is where the world's leading enterprises orchestrate AI-powered work. Our vision is to expand human capacity through superintelligence. And we're proving it's possible – through powerful, trustworthy AI that unites IT and business teams together to unlock enterprise-wide transformation. With WRITER's end-to-end platform, hundreds of companies like Mars, Marriott, Uber, and Vanguard are building and deploying AI agents that are grounded in their company's data and fueled by WRITER's enterprise-grade LLMs. Valued at $1.9B and backed by industry-leading investors including Premji Invest, Radical Ventures, and ICONIQ Growth, WRITER is rapidly cementing its position as the leader in enterprise generative AI. Founded in 2020 with office hubs in San Francisco, New York City, Seattle, Austin, Chicago, and London, our team thinks big and moves fast, and we're looking for smart, hardworking builders and scalers to join us on our journey to create a better future of work with AI. 📐 About the role This is where security meets innovation at enterprise scale. As a security engineer, applications at WRITER, you'll be building the security foundations that protect the AI systems powering some of the world's most recognizable brands. You'll work at the intersection of application security, AI infrastructure, and developer enablement—partnering with engineering teams to embed security into every line of code while ensuring our platform remains both powerful and trustworthy. The opportunity is massive: you'll help define how enterprise AI applications are secured, from threat modeling our LLM architectures to building automated security controls that scale across our growing platform. This isn't about saying "no"—it's about finding creative ways to say "yes, and here's how we do it securely." You'll tackle challenges that most security engineers never encounter: securing AI agents, protecting training data pipelines, and designing controls for systems that didn

JavaScriptTypeScriptPythonJava
W
📍 London, England, United Kingdom· Full-time· Remote
✓ High-confidence listingCompany trend -10%
Quick readStrong listing-quality and freshness signals

🚀 About WRITER WRITER is where the world's leading enterprises orchestrate AI-powered work. Our vision is to expand human capacity through superintelligence. And we're proving it's possible – through powerful, trustworthy AI that unites IT and business teams together to unlock enterprise-wide transformation. With WRITER's end-to-end platform, hundreds of companies like Mars, Marriott, Uber, and Vanguard are building and deploying AI agents that are grounded in their company's data and fueled by WRITER's enterprise-grade LLMs. Valued at $1.9B and backed by industry-leading investors including Premji Invest, Radical Ventures, and ICONIQ Growth, WRITER is rapidly cementing its position as the leader in enterprise generative AI. Founded in 2020 with office hubs in San Francisco, New York City, Seattle, Austin, Chicago, and London, our team thinks big and moves fast, and we're looking for smart, hardworking builders and scalers to join us on our journey to create a better future of work with AI. 📐 About the role Imagine stepping into a role where your code directly empowers the world's largest enterprises to safely adopt superintelligence. As a software engineer, generative ai at WRITER, you'll be at the forefront of expanding human capacity by building the secure, scalable foundation that allows our generative AI solutions to thrive in complex corporate environments. The impact of this work is massive – for example, in the consumer packaged goods industry alone, our AI adoption is driving 69% revenue increases and 72% cost reductions. This role is designed for a well-rounded engineering generalist who leans heavily into generative AI while bringing a whole-systems mindset to architectural design. If you thrive on proactivity without red tape and love owning projects from proposal to deployment, you'll shape the future of AI and contribute to a product that’s changing how the world works. This is a hybrid role based out of our San Francisco, New York City, or London hu

TypeScriptPythonReactPostgreSQL
W
📍 London, England, United Kingdom· Full-time· Remote
✓ High-confidence listingCompany trend -10%
Quick readStrong listing-quality and freshness signals

🚀 About WRITER WRITER is where the world's leading enterprises orchestrate AI-powered work. Our vision is to expand human capacity through superintelligence. And we're proving it's possible – through powerful, trustworthy AI that unites IT and business teams together to unlock enterprise-wide transformation. With WRITER's end-to-end platform, hundreds of companies like Mars, Marriott, Uber, and Vanguard are building and deploying AI agents that are grounded in their company's data and fueled by WRITER's enterprise-grade LLMs. Valued at $1.9B and backed by industry-leading investors including Premji Invest, Radical Ventures, and ICONIQ Growth, WRITER is rapidly cementing its position as the leader in enterprise generative AI. Founded in 2020 with office hubs in San Francisco, New York City, Seattle, Austin, Chicago, and London, our team thinks big and moves fast, and we're looking for smart, hardworking builders and scalers to join us on our journey to create a better future of work with AI. 📐 About the role Join WRITER's security team as a staff detection and response engineer and help protect the AI infrastructure that's transforming how the world works. You'll build sophisticated detection systems that identify attacks targeting our AI platform, training data, and model deployments while creating automated response capabilities that scale with our explosive growth. This isn't just traditional security work – you're defending cutting-edge AI/AGI systems against adversaries who are evolving their tactics as fast as AI itself advances. This role combines hands-on security engineering with strategic thinking to stay ahead of novel threats that don't exist in textbooks yet. You'll be the operational arm of our security function, translating threat intelligence into real-time detections, coordinating incident response across multiple teams, and hunting for sophisticated attacks across GPU clusters and distributed training environments. If you're excited by the challen

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