Principal Software Engineer

At Lilly, we unite caring with discovery to make life better for people around the world. We are a global healthcare leader headquartered in Indianapolis, Indiana. Our employees around the world work to discover and bring life-changing medicines to those who need them, improve the understanding and management of disease, and give back to our communities through philanthropy and volunteerism. We give our best effort to our work, and we put people first. We're looking for people who are determined to make life better for people around the world.

About The Technology Organization
Technology at Lilly builds and maintains capabilities using pioneering technologies like most prominent tech companies. What differentiates Technology at Lilly is that we create new possibilities through tech to advance our purpose – creating medicines that make life better for people around the world, like data driven drug discovery and connected clinical trials. We hire the best technology professionals from a variety of backgrounds, so they can bring an assortment of knowledge, skills, and diverse thinking to deliver solutions in every area of our business.

About The Business Function
The Software Product Engineering (SPE) team is a specialised engineering group that delivers strategic solutions and differentiated capabilities. We take a forward-thinking approach, focusing on an enterprise platform and product mindset, ensuring that the solutions we build can be leveraged across Technology teams for broader impact and efficiency.

Job Title: Principal Software Engineer
Role Summary
As a Principal Software Engineer, you will lead the design, development, and delivery of business-critical applications across both frontend and backend systems. You will set engineering standards, mentor junior engineers, and drive technical excellence in cloud-native, scalable, and maintainable solutions. Your work will directly impact the reliability, performance, and value of our software products.

What You'll Be Doing

• Develop and contribute to frontend and backend frameworks supporting business-critical applications using JavaScript frameworks like ReactJS and
• Design and build scalable, reusable, and maintainable backend services and APIs with , , PostgreSQL, and cloud-native patterns.
• Replace commercial off-the-shelf (COTS) systems with modern, in-house scalable solutions leveraging AWS (ECS Fargate, Lambda, S3, RDS, CloudFormation, CloudWatch) and containerisation (Docker).
• Develop user-facing interfaces using React (Material-UI, Bootstrap, React Router, Redux Toolkit, Emotion, ) with a focus on performance, accessibility, and Core Web Vitals.
• Coach and mentor junior engineers and help raise the overall technical bar.
• Define and maintain engineering standards, including CI/CD (GitHub Actions, Jenkins, AWS CodeBuild) and code quality practices (ESLint, Prettier, Husky, lint-staged).
• Collaborate across teams to deliver impactful features with measurable value.
• Leverage AI tools like GitHub Copilot to accelerate development workflows, improve code quality, and reduce boilerplate.
• Lead the authoring of technical documents, including high-level design documents, architectural blueprints, technical standards, and best practice guidelines to drive technical excellence and cross-team alignment.
• Demonstrate proficiency in prompt engineering to effectively guide AI tools in generating optimal and context-aware code solutions.
• Use AI-assisted pair programming to support rapid prototyping, test case generation, and debugging.
• Encourage and mentor team members on responsible and secure use of AI in the software development lifecycle.

How You Will Succeed

• Design and implement robust APIs (RESTful) and microservices using and frameworks like or
• Build and manage scalable backend services with fault-tolerance, performance, and security in mind.
• Integrate with cloud platforms (AWS, GCP, or Azure) and manage infrastructure with CI/CD tools like GitHub Actions or Jenkins.
• Work with databases such as MongoDB and PostgreSQL to store and retrieve structured and unstructured data efficiently.
• Build responsive and accessible UIs using React, with supporting libraries such as Material-UI, Bootstrap, React Router, Redux Toolkit, Emotion,
• Implement modern UI development practices, including component-based design and state management (Redux, Context API).
• Collaborate with designers and UX teams to implement pixel-perfect interfaces.
• Optimise front-end applications for performance and Core Web Vitals.
• Apply accessibility best practices and WCAG 2.2 standards.
• Lead code reviews, guide junior engineers, and build production-grade software.
• Contribute to open-source projects or lead technical discussions and architecture reviews.

What You Should Bring

• Strong proficiency in and supporting libraries (Material-UI, Bootstrap, Redux Toolkit, React Router, Emotion, ).
• Solid understanding of JavaScript (ES6+), TypeScript (4.x–5.x), HTML5, and CSS3/SCSS/Sass.
• Proficient in backend development with (20.x+), x+),
• Experience with RESTful and GraphQL APIs, microservices architecture, and real-time communication (e.g., WebSockets).
• Practical experience with AWS (ECS Fargate, Lambda, S3, RDS, CloudFormation, CloudWatch), and containerisation (Docker).
• Familiarity with state management tools (Redux, Context API).
• Strong testing experience using tools like Jest, React Testing Library, Cypress, Playwright.
• Comfortable with frontend build tools like Webpack (4.x/5.x), Vite, Babel (7.x), Gulp, NPM, and linters like ESLint, Prettier, Husky, lint-staged.
• Experience working with CI/CD pipelines, source control (Git), and modern DevOps workflows.
• Exposure to domain-driven design (DDD), serverless architecture, or event-driven systems.
• Knowledge of accessibility best practices and WCAG 2.2 standards.
• Experience in regulated industries (e.g., Life Sciences) is a bonus but not required.

Basic Qualifications And Experience Requirement

• Bachelor's degree in computer science, Computer Engineering, or a related technical field.
• 8+ years of hands-on software development experience across frontend and backend systems.
• Demonstrated ability to lead code reviews, guide junior engineers, and build production-grade software.
• Strong foundation in computer science fundamentals, software architecture, and cloud-native patterns.
• Effective verbal and written communication skills.
• Ability to work collaboratively across backend, frontend, DevOps, and product teams.
• A high degree of intellectual curiosity and commitment to continuous learning.

Additional Skills/Preferences

• Familiarity with Core Web Vitals and frontend performance optimisation techniques.
• Experience with component-driven development using a design system (e.g., Material UI, Ant Design).
• Contributions to open-source projects or experience leading technical discussions and architecture reviews.
• Experience in regulated industries (e.g., Life Sciences) is a bonus but not required.

Lilly is dedicated to helping individuals with disabilities to actively engage in the workforce, ensuring equal opportunities when vying for positions. If you require accommodation to submit a resume for a position at Lilly, please complete the accommodation request form ) for further assistance. Please note this is for individuals to request an accommodation as part of the application process and any other correspondence will not receive a response.

Lilly does not discriminate on the basis of age, race, color, religion, gender, sexual orientation, gender identity, gender expression, national origin, protected veteran status, disability or any other legally protected status.