Senior Python Developer/ Engineer

Cognizant; London Colney; On-site; GBP 65,000 - 90,000; Full time

Job summary

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

The role emphasizes Python backend development with serverless AWS, RESTful APIs, and Docker-based containerization, collaborating with product teams and stakeholders to translate requirements into robust technical solutions.

Qualifications

• Professional software engineering experience with Python and backend frameworks.
• Extensive experience building RESTful APIs, microservices and backend services.
• Hands-on AWS cloud experience including Lambda, ECS Fargate, API Gateway, DynamoDB, S3.
• Experience with serverless deployment and containerized apps (Docker, ECS/Fargate).
• Familiar with security: OAuth2, JWT, OpenID Connect, API Keys.
• Knowledge of relational and NoSQL databases; Terraform and/or CloudFormation advantageous.
• Experience in Agile/Scrum delivery environments and CI/CD pipelines.

Responsibilities

• Develop secure, scalable features for the Digital Onboarding Service using Python in a serverless/cloud-native setup.
• Design and maintain RESTful APIs and microservices, with a NextJS/React frontend in scope.
• Collaborate with Architects, product managers, and clients to translate requirements into robust solutions.
• Implement integrations with internal systems and external APIs using REST and event-driven patterns.
• Apply SOLID and clean architecture principles; contribute to testing, performance, and reliability.
• Support automated deployment pipelines and work with DevOps on application delivery.
• Contribute to documentation and knowledge sharing within the team.

Skills

Python

RESTful APIs

Microservices

Serverless architecture

Agile delivery

OAuth2 / JWT / OpenID Connect

Distributed systems

OpenAPI / Swagger

Tools

FastAPI

Flask

Docker

AWS (Lambda, ECS Fargate, API Gateway, DynamoDB, S3)

Terraform / CloudFormation / AWS CDK

GitHub Actions / CI/CD tooling

Job description

We are looking for a talented Python Engineer with hands‑on experience building high quality, scalable server less applications. You will work closely with the Lead Engineer to design, build, and enhance the Digital Onboarding Service (DOS) used across the client API Platform.

This role is ideal for someone who is strong in Python, confident working with architects and APIs, and comfortable delivering features within an Agile delivery team.

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.

Requirements

• 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.

Nice-to-Have Skills

• Experience with React/NextJS.
• Experience with automated testing frameworks such as Pytest, Unit Testing, Integration Testing, and API Testing.
• Exposure to WebSockets, event‑driven architectures, or real‑time data patterns.
• Familiarity with modern authentication approaches such as OAuth2, OpenID Connect, JWT, and AWS Cognito.
• Experience with OpenAPI/Swagger specifications and API lifecycle management.
• Experience with CI/CD tools such as GitHub Actions, Azure DevOps, Jenkins, or AWS CodePipeline.