Lucian Văcăroiu, Developer in Bucharest, Romania
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Lucian Văcăroiu

Verified Expert  in Engineering

Javascript Developer

Bucharest, Romania
Toptal Member Since
June 19, 2017

Lucian has 17 years of professional experience as a full-stack developer and solution architect. He's built web apps optimized for large-scale production performance and worked extensively with PHP, JavaScript (including Node.js, Vue, and React), SQL, NoSQL database back ends, and many AWS technologies. His skill set includes advanced topics like serverless architecture and modern data-mapping design.


St. Jude Children's Research Hospital
Laravel, PHP, Vue, D3.js, OAuth 2, REST APIs, Docker, Kubernetes
Motoreco Parts
Serverless, Vue, Laravel, PHP, MySQL, Agile Project Management...
Toptal Client
Amazon Web Services (AWS), AWS CodePipeline, Amazon DynamoDB, AWS Lambda, React...




Preferred Environment

Docker, Neovim, Tmux

The most amazing...

...thing I've built working via Toptal has been a data visualization platform for pediatric cancer research for St. Jude Children's Research Hospital.

Work Experience

Developer Lead

2020 - 2023
St. Jude Children's Research Hospital
  • Recognized at the American Association for Cancer Research (Abstract 1901 in April 2022 and Abstract 3163 in 2023) for developing VisComm and PeCan, innovative cloud-based platforms enhancing pediatric cancer research and data navigation.
  • Engineered a robust web development foundation using Laravel, Livewire, and Docker with Lando, focusing on cross-team collaboration, enhanced productivity, and rapid onboarding processes.
  • Implemented a versatile multi-tenant authentication system using Auth0, integrating St. Jude SSO for seamless access across all Bioinformatics Department platforms, enhancing user experience and security.
  • Designed and developed a secure, scalable JWT and OAuth API for seamless data integration between legacy systems and new applications, facilitating efficient collaboration across all St. Jude Bioinformatics Department platforms.
Technologies: Laravel, PHP, Vue, D3.js, OAuth 2, REST APIs, Docker, Kubernetes

Engineering Manager | Software Architect Product | Manager

2019 - 2023
Motoreco Parts
  • Led a product team of two full-stack developers and a UI/UX designer, effectively aligning stakeholder objectives with team capabilities to develop products meeting company needs.
  • Designed and led a scalable, serverless PHP and AWS solution for a large auto parts retailer. Automated all operations, including auto-scaling for online traffic, warehousing, supplier processing, and a GraphQL API back-end.
  • Crafted a comprehensive CI/CD pipeline integrating AWS services such as Lambda, API Gateway, Aurora, S3, Elasticache, and Elasticsearch, along with GitLab and Cypress for seamless automated testing.
Technologies: Serverless, Vue, Laravel, PHP, MySQL, Agile Project Management, Product Leadership

Software Architect

2019 - 2019
Toptal Client
  • Designed the complete system architecture for a large-scale CMS, focusing on high availability and continuous integration/delivery.
  • Designed AWS technology orchestration using AWS Lambda and AWS DynamoDB for robust and scalable performance.
  • Researched dependencies and available open-source software packages in the React/Node.js ecosystem that could facilitate quicker delivery while meeting all the client requirements.
Technologies: Amazon Web Services (AWS), AWS CodePipeline, Amazon DynamoDB, AWS Lambda, React, Node.js

Senior Node.js Developer

2019 - 2019
  • Worked on a product that is under very strict NDA and is being actively used for data science and analytics by publicly traded Fortune 500 companies.
  • Successfully identified and improved the architecture and performance pain points across the front end in one of the client's flagship products.
  • Navigated and adapted to a very high-security development workflow.
Technologies: React, Node.js

Lead Node.js/React Developer

2018 - 2019
  • Architected a complete end-to-end microservice-based scalable and high-availability front-end and back-end solution based on AWS services and leveraging open-source technologies like React and Node.js.
  • Developed an entire CI/CD pipeline consisting of a complex orchestration of multiple AWS services, including Lambda, API Gateway, DynamoDB, and Aurora, to build, test, and deploy several serverless APIs and client apps.
  • Designed and developed several serverless GraphQL APIs with Node.js, leveraging multiple AWS services, including Cognito, Lambda, API Gateway, DynamoDB, and Aurora to serve as a back end for multiple client apps.
  • Designed and developed several responsive PWA client apps using a React/Redux/Sagas stack, leveraging AWS Cognito for user authentication and authorization, including authorization and access to the aforementioned GraphQL APIs.
Technologies: Amazon Web Services (AWS), DevOps, GraphQL, AWS CodePipeline, Amazon Aurora, Amazon DynamoDB, AWS Lambda, Serverless, React, Node.js

Lead React Developer

2017 - 2017
ARTA Shipping
  • Developed a React/Redux/Sagas progressive web app (PWA) solution to support the client's fine-art shipping management business.
  • Refactored and adapted legacy UI to the modern responsive and async requirements of a PWA.
  • Reversed-engineered legacy Python code to figure out endpoint architecture and interfaces for a legacy API with loosely maintained documentation.
Technologies: Python, Sagas, Redux, React

Lead React Developer

2017 - 2017
Moment Studios
  • Developed a React/Redux/Sagas PWA solution to support the client's mobile app with Instagram-like functionality. Requirements included consuming a pre-existing JWT-authentication-based REST API.
  • Built an independent PWA solution to act as a back-office/administration interface that the client's employees would use to moderate user content.
  • Got up to speed quickly, self-managed and kept the project on track with minimal project specifications.
Technologies: Firebase, Sagas, Redux, React

Freelance Consultant

2011 - 2017
  • Refined back-end code for Green Horse Games` MVP, a browser-based racing game, on the heels of their round A.
  • Implemented 2Parale Affiliate Network's long-term DevOps and SysOps strategies, as well as consulted on expanding their tech team and development efforts.
  • Architected and developed the first local/regional cashback platform.
  • Developed a PWA for analyzing the European used car market, using a mathematical model to estimate fair prices and maintenance costs for various vehicles.
  • Architected and developed a multi-campaign tracking system for mobile-app user acquisition with Facebook ads and the Facebook Ads API for
  • Created and developed a web-based A/B testing solution for PPC and PPV ad campaigns for Affiliate Window Ltd based on a mathematical model for statistical significance.
Technologies: Amazon Web Services (AWS), PowerMTA, MySQL, PHP, Ruby on Rails (RoR), Ruby, DevOps, AWS CodePipeline, Amazon Aurora, Amazon DynamoDB, AWS Lambda, Serverless, React, Node.js, Consulting, Leadership, Architecture


2009 - 2011
eRepublik Labs
  • Oversaw the overall staffing strategy as well as day-to-day technical operations, including managing the supporting technical and financial infrastructure necessary for a team of roughly 30 people.
  • Initiated and led the effort to architect and implement what were, at the time, bleeding-edge DevOps strategies when the term DevOps was relatively unknown.
  • Helped the company transition its flagship product, a browser-based MMO, into the modern age and support a fast-expanding user base, on the heels of their series A funding.
Technologies: IBM WebSphere, MySQL Clustering, DevOps, LAMP, Ruby on Rails (RoR), Ruby, CTO, Leadership

Client Testimonial (via Toptal)

"I have had the pleasure of working closely with Lucian since February 2020. He is an excellent team member, software engineer, and collaborator. Lucian is one of the most well-rounded, talented software engineers I have worked with, and he effortlessly understands the full concept of any project he is on. He is confident in his decisions and communicates his solutions well[,] but is also open to alternative solutions to accommodate the company and team. While on our team, he has been the sole developer on several crucial projects and always produces top-notch products. Lucian is not only an excellent developer but a welcoming, hilarious, and easy-going coworker. I would jump at the opportunity to work on a team with Lucian anytime." – Kirby Birch, Product Manager, St. Jude Children's Research Hospital

Client Testimonial

"Lucian worked diligently under a tight deadline to produce a detailed and solid proposed technical approach for a large-scale software project. He is someone that I will certainly want to work with again in the future." – Toptal Delivery Manager

Client Testimonial (via Toptal)

"We can without a doubt say that with Lucian's know-how and deep understanding of front and back-end development, we could safely concentrate on the business end and trust that he managed the architecture and development. Never was there a time we felt that we had to double-check and he would always be pro-active in coming back with suggestions on how to solve a particular issue. We always considered him a full trusted member of our team. Another testament to his expertise was applying his experience to something that was new for both parties, developing serverless on AWS with all the moving parts that that entails." – Niklas Nåsén, co-founder

Client Testimonial

"Lucian is a great CTO with a strong entrepreneurial streak. He is a straight talker that will tell you how things are and is not afraid of taking risks where needed. A great person to have on any team and it was a privilege to work with him." – Alexis Bonte, CEO at eRepublik Labs Limited

Client Testimonial

"If your internet company is in trouble or you want to take it to the next level, you need a Lucian. His results-oriented mindset is completed by great tech skills and online sales experience. He is the type of person that can solve the biggest problems that your company has. And you will realize this after the first conversation with him." – George Lemnaru, CEO of Green Horse Games
2003 - 2005

Completed Credits Towards a Master’s Degree in Business Adminstration

Hyperion University - Bucharest, Romania


React, Node.js, jQuery, REST APIs, Vue, Flexbox, D3.js


Git, Terraform, Webpack, Lando, PhpStorm, PowerMTA, Tmux


Redux, Express.js, Laravel, Sails.js, Bootstrap, React Native, Ruby on Rails (RoR), OAuth 2


SQL, GraphQL, HTML, CSS, ECMAScript (ES6), ES7, SCSS, JavaScript, PHP, Gremlin, HTML5, CSS3, Solidity, Ruby, Python


REST, Continuous Integration (CI), DevOps, Management, Agile Project Management


Docker, Amazon Web Services (AWS), AWS Lambda, Amazon EC2, Blockchain, MacOS, LAMP, IBM WebSphere, Firebase, Kubernetes


MongoDB, MySQL, Amazon DynamoDB, NoSQL, Amazon Aurora, MySQL Clustering


Serverless, Data Architecture, Software Architecture, Sagas, Freelancing, Architecture, Software Design, AWS CodePipeline, Leadership, Software, CTO, Product Leadership, Consulting, Neovim

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