React Fullstack Developer

10/2022 – 11/2022

PROJECT
Sign-up wizard for fitness club guests

CLIENT
International chain of premium fitness clubs

SKILLS
Next.js, React, JavaScript, REST, Node, PostgreSQL, Jest, Testing Library, Git, Kanban

ACHIEVEMENTS & RESPONSIBILITIES
- Implemented a sign-up wizard for club guests with TypeScript and Next.js
- Reduced the amount of boilerplate form and validation logic by using React Hook Form and Zod
- Created a microservice to abstract away more complex edge cases from the frontend
- Separated request handling, business logic, and integration of 3rd-party APIs with a layered architecture

Node.Js, Postgresql, React (JavaScript library), Test Automation, Typescript

7/2020 – 9/2022

PROJECTS
Suite of premium web application products to streamline the process of buying a house

CLIENT
Germany's leading online marketplace for real estate

SKILLS
React, Redux, TypeScript, REST, Express, PostgreSQL, AWS, cfn, Storybook, Jest, Testing Library, Cypress, Playwright, CI/CD, Jenkins, GitHub Actions, Git, ScrumBan

ACHIEVEMENTS & RESPONSIBILITIES
- Developed a suite of premium web application products to streamline the process of buying a house
- Helped grow the revenue from 1.3M EUR in the first year to 10M EUR in the third year (based on 30,000 paying subscribers)
- Consulted several teams on re-writing legacy fronted apps using a modern tech stack and DevOps best practices
- Conducted knowledge sessions to share React Testing Library best practices with other teams

GENERATOR FOR A PROFESSIONAL APPLICATION PORTFOLIO
- Spear-headed a complex architectural application change over several projects after major compatibility-breaking change in the popular React library react-router
- Helped team negotiate their poor design decision with answers to how and where to handle errors, asynchronous side effects, and more complex business logic
- Inherited a legacy payment project with outdated code that needed urgent adjustments and improved the code quality and coverage from 50% to 90% over the course of 3 months
- Used Test-first Programming to drive the development of the frontend and Storybook to create components more efficiently in isolation according to the designs provided by the UX designer
- Reduced build time of a backend project from 10 minutes to 2 seconds by migrating the project from Webpack to esbuild
- Paired with 6 developers on vertically sliced User Stories and consulted the Product Owner on how to create good User Stories

PROPERTY VALUATION (SPRENGNETTER)
- Reimplemented a property valuation flow as a stand-alone wizard (micro-frontend) that now can be integrated by other departments
- Implemented an accessible video player component with hidden controls for showing ads
- Maintained a Serverless backend with a DynamoDB hosted with AWS Lambda and AWS API Gateway
- Introduced test and storybook decorators to make testing React components easier and faster
- Upgraded a CI/CD pipeline used by hundreds of software engineers to deploy a mission-critical service

ASSESSMENT OF STRUCTURAL PROPERTY DAMAGES (DEKRA)
- Developed a React app to evaluate structural property damages with the help of an API provided by DEKRA • Mobile-first responsive web design using clean layout techniques and a bootstrap-like styling library
- Helped migrate the images of several projects from PNG to responsive WebP images using Webpack
- Created e2e test suites with Cypress and Playwright and improved the error output with custom reporters • Rolled out new features to end-users gradually using Optimizely feature toggles and A/B tests

DASHBOARD TO MANAGE AND OPTIMIZE MORTGAGE PAYMENTS
- Refactored shared class-based React components (such as wizards, modals, and carousels) to functional React components using custom hooks
- Increased the accessibility (a11y) of several apps by migrating Enzyme tests to React Testing Library and testing frontend components through the „eyes“ of the end-users
- Migrated a Java-based microservice to Express and added PostgreSQL schema migrations using Knex
- Acted as DevOps Support of the Week monitoring the team’s systems and reviewing 3rd-party pull requests

CREDIT SCORE CERTIFICATE (SCHUFA)
- Added page and event tracking of user activities with Google-Analytics-like service
- Fine-tuned flaky e2e tests that started failing due to race conditions after migrating to faster hardware
- Helped the team to stay focused by facilitating Agile ceremonies, including Retrospective, Daily Standup, and Iteration planning

Amazon Web Services (AWS), JavaScript, Node.Js, React (JavaScript library), Test Automation, Typescript

4/2020 – 6/2020

PROJECT
Responsive React app for mastery tracking

CLIENT
Provider of corporate IT training

SKILLS
React, Redux, Bootstrap, JavaScript, AWS, REST, Serverless, Swagger, DynamoDB, Storybook, Jest, Enzyme, Codecept, CircleCI, Agile

ACHIEVEMENTS & RESPONSIBILITIES
• Developed a single-page SaaS application with a clean architecture that separates frontend components
(React), central application state (Redux), and asynchronous state transitions (Thunks)
• Used a test-first approach to drive the implementation with acceptance, integration, and unit tests
• Implemented reusable react components such as wizards, modals, carousels, and input components
• Shipped new features on a daily basis using continuous delivery with CircleCI, AWS, and NPM Scripts
• Created a localized app experience with the help of i18n-libraries like react-intl and i18next
• Maintained an Express-based mock API to enable local development of the React frontend
• Collaborated closely with Product Owner to respond to continuously changing & increasing project scope

Node.Js, React (JavaScript library), Test Automation