# David O'Sullivan

> Software Engineer

Location: United States, United States
Profile: https://flows.cv/davidosullivan

Full-Stack Javascript engineer with a multi-disciplinary, people-oriented background. Passionate about continuous learning and providing performant, maintainable code. Experienced building scalable applications with React (Router, Hooks), Redux (Thunk), Node, Express,  SQL - Postgres/MySQL, NoSQL - MongoDB/Mongoose, RESTful APIs, OOP, AWS, Docker, Travis CI, TDD - Jest - Enzyme, Webpack, HTML/CSS/Sass, Git, Agile/Scrum

Recent talks: 
-Javascript: The Hard Parts (Callbacks & Higher Order Functions, Closure, OOP) Hosted through Build with Code LA (Monthly talks 2020/2021).

Introduction to Javascript (HTML/CSS, Variables & Looping, Functions & Objects) Hosted through Build with Code NYC (Monthly talks 2019/2020).

-Implementing React Hooks (October 2019).

When not leading teams and putting down code, you can find me reading Brandon Sanderson or playing any board game I can find. Always open to connect with other humans.

## Work Experience
### Senior Software Engineer @ Codesmith
Jan 2019 – Jan 2021 | Los Angeles, California, United States

### Software Engineer @ Consultare Inc.
Jan 2019 – Jan 2019 | Greater New York City Area
- Utilized a Node runtime with Express framework, enabling a Model-View-Controller architecture allowing for better code maintainability.

- Leveraged JWTs to authenticate requests to LinkedIn API, as well as securely transferring data between the application client and servers.

- Instantiated a PostgreSQL database for guaranteed validity of transactions, providing centralized, secure, ACID-compliant data records.

- Integrated OAuth 2.0 for LinkedIn to improve authentication UX and enhance security without sacrificing aggregation of end-user data.

- Utilized Passport in the authentication process to allow rapid serialization/deserialization of user profiles and descriptive error handling.

- Implemented Bcrypt to hash passwords with salts to encrypt sensitive user inputs, preventing possible rainbow table attacks.

- Implemented Redux architecture for structural best practices, improving scalability and ensuring data immutability to ease debugging by centralizing state, dividing application concerns into specific modules, and eliminating redundant prop drilling and complex prop chains.

- Incorporated Redux Persist to cache the store between page loads, increasing page responsiveness on load and creating better UX.

- Implemented Apollo-Client to effectively manage queries and mutations sent to the server with purposeful error management.

- Leveraged Jest for TDD, utilizing snapshot testing to ensure correct React component functionality and enabling continuous integration.

- Utilized Enzyme for TDD, unit testing to verify component structure and catch unwanted side effects within the application

### Interview Overflow | web application enabling users to view and post questions from interviews @ Open Source
Jan 2019 – Jan 2019
- Implemented React Router for dynamic client-side routing, boosting loading performance and minimizing server calls within a SPA.

- Incorporated styled-components within React components to reduce code loaded by users as well as enhancing maintainability of styles.

### Out Of The Loop | web application that renders articles from different news sources in a SPA @ Open Source
Jan 2019 – Jan 2019
- Utilized the Mongoose ODM to enforce a typed schema for end-user data without losing the flexibility of a non-relational database, ensuring that while application state grows database scaling will remain consistent and reliable for all business-logic needs.

- Implemented a Node server to asynchronously handle concurrent connections with a single-threaded non-blocking I/O event loop to minimize server latency and ensure a responsive UX even during a high volume of concurrent requests


## Education
### International Asian Studies Programme
The Chinese University of Hong Kong

### Bachelor's Degree (Hons)
Trinity College Dublin


## Contact & Social
- LinkedIn: https://linkedin.com/in/osullid7

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Source: https://flows.cv/davidosullivan
JSON Resume: https://flows.cv/davidosullivan/resume.json
Last updated: 2026-03-30