Senior Python Engineer – Cloud, APIs & Serverless

Cognizant; City of Westminster, Greater London; On-site; GBP 70,000 - 110,000; Full time

Job summary

Cognizant is seeking a Python Engineer to design, build and enhance the Digital Onboarding Service within the client API Platform. You will work with the Lead Engineer in an Agile team to deliver high quality, scalable features.

You will develop RESTful APIs and microservices in Python (FastAPI/Flask), using serverless and containerized AWS architecture (Lambda, ECS Fargate, API Gateway). You’ll ensure secure, reliable delivery and collaborate with product and DevOps teams.

Qualifications

• Professional software engineering experience.
• Strong commercial experience with Python using FastAPI, Flask, or similar backend frameworks.
• Extensive experience developing RESTful APIs, microservices, and backend services.
• Strong hands‑on experience with AWS cloud services, including ECS Fargate, Lambda, API Gateway, DynamoDB, S3, SNS, SQS, EventBridge, Step Functions, IAM, Secrets Manager, and CloudWatch.
• Strong experience with serverless deployment and architecture patterns.
• Experience developing and deploying containerized applications using Docker and AWS ECS/Fargate.
• Experience integrating with third‑party APIs, enterprise platforms, and external services.
• Strong understanding of software design patterns, object‑oriented programming principles, clean code practices, and distributed system design.
• Experience implementing API security using OAuth2, JWT, OpenID Connect, API Keys, and secure authentication/authorization mechanisms.
• Experience with relational and NoSQL databases such as PostgreSQL, MySQL, Aurora, or DynamoDB.
• Experience with Infrastructure as Code (Terraform, AWS CDK, or CloudFormation) is highly desirable.
• Good understanding of software deployment processes, application monitoring, logging, and environment management.
• Experience working in secure or regulated environments (e.g., healthcare, finance, government) is beneficial.
• Understanding of data protection, access control, and secure software development practices.
• Experience working within Agile/Scrum delivery environments.

Responsibilities

• Develop high quality, secure, and maintainable features for the client Digital Onboarding Service using Python on the backend in a serverless and containerized architecture with a NextJS/React client frontend.
• Design, develop, and maintain scalable RESTful APIs and microservices using Python frameworks such as FastAPI or Flask.
• Build and support cloud-native solutions leveraging AWS services including Lambda, ECS Fargate, API Gateway, DynamoDB, S3, Secrets Manager, and CloudWatch.
• Work closely with the Lead React Engineer, Technical Architects, and Engineering teams to implement technical designs, architectural patterns, and coding standards.
• Collaborate with product managers, designers, and client stakeholders to translate business requirements into robust technical solutions.
• Design and implement integrations with internal client systems and external third-party APIs using REST, webhooks, and event-driven integration patterns.
• Apply software engineering best practices, including SOLID principles, Clean Architecture, Repository Pattern, Factory Pattern, Strategy Pattern, Dependency Injection, and other design patterns to create maintainable and extensible solutions.
• Implement resilient solutions using retry mechanisms, error handling strategies, circuit breaker patterns, dead-letter queues, and asynchronous messaging.
• Work within established development and release processes to ensure high-quality software delivery. Contribute to code quality, automated testing, performance optimization, and system reliability improvements.
• Support CI/CD deployment pipelines and collaborate with DevOps teams to ensure smooth and reliable application delivery.
• Contribute to documentation, knowledge sharing, and continuous improvement within the engineering team.

Skills

Python

FastAPI/Flask

REST APIs

AWS

Serverless

Docker

CI/CD

OAuth/JWT

Agile/Scrum

Tools

AWS ECS/Fargate

OpenAPI

Terraform

CloudWatch

Job description

Cognizant is seeking a Python Engineer to design, build and enhance the Digital Onboarding Service within the client API Platform. You will work with the Lead Engineer in an Agile team to deliver high quality, scalable features.

You will develop RESTful APIs and microservices in Python (FastAPI/Flask), using serverless and containerized AWS architecture (Lambda, ECS Fargate, API Gateway). You’ll ensure secure, reliable delivery and collaborate with product and DevOps teams.