Tudor Filip Stupariu, Developer in Cluj-Napoca, Romania
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Tudor Filip Stupariu

Verified Expert  in Engineering

Software Developer

Cluj-Napoca, Romania
Toptal Member Since
October 17, 2019

Tudor is a full-stack software developer who's focused on building with JavaScript technologies. He's made apps ranging from mobile and web front end to the server-side. Along with being equally comfortable working in teams all sizes and as a solo developer, Tudor is quick to adapt to unexpected situations. Tudor enjoys freelancing because of the sense of responsibility and accomplishment he gets when delivering the client’s end product.


Sports Card Investor, LLC
JavaScript, CSS, Next.js, Express.js, React, PostgreSQL, HTML, Node.js...
Hybrid Apps, ECMAScript (ES6), Android, iOS, React Native, Firebase, React...
Hybrid Apps, ECMAScript (ES6), Android, iOS, React Native, React, JavaScript




Preferred Environment

Git, WebStorm, MacOS

The most amazing...

...feature set I've coded was making an Android phone act as a POS device by locking the user in the app and integrating third-party thermal printer libraries.

Work Experience

Full-stack Developer

2020 - 2024
Sports Card Investor, LLC
  • Developed and scaled a platform from databases of thousands of collectibles to millions. This included adding new features, creating new products and MVPs, and fixing issues within business constraints.
  • Worked on data processing pipelines to achieve data filtration, accuracy, and scaling using SQL databases, AWS Lambdas, AWS Simple Queue Service (SQS), and other needed technologies.
  • Created a process used to update the sales data related to collectibles continuously. This process was infinitely adjustable, prioritizing some collectibles over others, together with forecasting and estimation metrics.
  • Built a collection tracking system where users could retroactively measure their collections. This went past a simple collection management system since it also included the ability to edit things in the past according to values.
  • Developed an alert system so that users could be notified whenever different parameters of certain collectibles changed (like value or sales volume).
  • Built a complex admin tool for managing and monitoring the collectibles and data flows. This tool added certain smart limits so that admins could have a safety net over their actions.
  • Iterated and built several POCs and MVPs for different features and projects. Some materialized into mature, grown products adjacent to the core applications.
  • Wrote and constantly optimized database queries and data sources. Used technologies like AWS OpenSearch, PostgreSQL, and MongoDB to achieve smart searching algorithms for a better end-user experience.
  • Created an index tracking system that allowed admins to replicate indices like the S&P 500 but for collectibles. This includes past value tracking, managing set indices, and their visibility to the public in the UI.
  • Worked closely with the product team to determine the best solutions for different circumstances while advising on development paths dependent on feature importance, scalability concerns, and cost.
Technologies: JavaScript, CSS, Next.js, Express.js, React, PostgreSQL, HTML, Node.js, AWS Lambda, Lambda Functions, Databases, Amazon S3 (AWS S3), Data Processing

Full-stack Mobile Developer

2020 - 2020
  • Created the architecture of a React Native mobile application from scratch.
  • Implemented in-app purchases for Apple's app store.
  • Created the designs for all of the screens in Figma.
  • Handled picture uploads/fetches in order to make an efficient loading time in a picture-heavy mobile application.
  • Built an efficient Firebase structure in order to minimise costs and improve performance.
  • Built the authentication with email verification and front-end logic of the application.
  • Implemented dynamically loading photo streams for multiple screens inside the application.
Technologies: Hybrid Apps, ECMAScript (ES6), Android, iOS, React Native, Firebase, React, JavaScript

React Native Developer

2020 - 2020
  • Built the screens for the entire authentication flow, including multiple ways to copy/paste/share items.
  • Created a dynamically generated QR code that updates at a given interval.
  • Created an encrypted QR code that used multiple data points and would only be properly read by a proprietary scanner app.
  • Implemented large forms on single screens together with keyboard interactions.
Technologies: Hybrid Apps, ECMAScript (ES6), Android, iOS, React Native, React, JavaScript

Front-end Developer

2019 - 2020
  • Rewrote the email templates to properly display on all email clients, including old versions of Outlook.
  • Split the front-end components into separate packages for reuse between different web applications.
  • Refactored major components containing custom forms and validations.
  • Created and rewrote landing pages to comply with newer standards like React Hooks.
  • Wrote a package for validating custom forms.
  • Locally synchronized data on forms with data from the server in order to provide a seamless experience for the end user.
  • Quickly developed custom pages for tasks that needed to be deployed as soon as possible.
Technologies: HTML, ECMAScript (ES6), Web, HTML5, React, JavaScript, SCSS, Node.js

JavaScript Developer

2019 - 2019
Bonfire Interactive
  • Handled large forms with specific selection interactions.
  • Created paginated tables for handling large amounts of data.
  • Implemented security and authentication handling between routes.
Technologies: HTML, ECMAScript (ES6), Web, HTML5, Firebase, React, JavaScript, Material UI, CSS

JavaScript Developer

2019 - 2019
  • Developed a push-notification system for a VoIP application, including handling special VoIP notifications on iOS.
  • Implemented an in-app purchase system both on React Native and its Node.js server counterpart.
  • Built a way to manage contacts both stored on the phone or Google account and in the app's own contact management system.
  • Created a reusable, customizable, and efficient component for displaying different banner messages to the user in a React Native application.
  • Debugged and fixed a lot of issues with the application such as not waking up on calls or messages and implemented specific VoIP behaviors.
Technologies: Hybrid Apps, MongoDB, ECMAScript (ES6), Express.js, REST APIs, React Native, React, JavaScript, Node.js

JavaScript Developer

2018 - 2019
  • Helped develop a specialized recruitment platform using Next.js and Node.js.
  • Created an app's admin dashboard; the app dealt with specialized recruiting that handled the entire data of the platform.
  • Developed a set of features for a React Native Android app that denied a user the possibility of closing or exiting the application without a PIN code even between phone restarts.
  • Built a mobile application in React Native for small store owners that needed to handle multiple large forms using React Native and MobX.
  • Composed migration scripts that altered the databases in multiple environments when issues and errors occurred.
  • Developed a native integration for React Native that allowed an application to communicate with a built-in or Bluetooth thermal printer for printing receipts from an Android or iOS device.
  • Created a React Native component designed to handle the layout of the keyboard and buttons for screens that contained forms with more than ten input types.
  • Built a feature that allowed translating a JSON template for an invoice into a rudimentary layout system that a thermal printer would understand.
  • Handled a production database using Firebase complete with optimizations for speed and efficiency.
Technologies: Hybrid Apps, HTML, ECMAScript (ES6), Express.js, Android, iOS, REST APIs, Web, HTML5, React Native, Firebase, React, JavaScript, CSS, Next.js, Node.js

Web Developer

2017 - 2018
  • Built an internal tool for the HR department to help them organize their candidates and the interview flow using React and .NET Core.
  • Created an internal tool for the system administration department to help them keep track of the computers and servers deployed throughout the company using Angular and .NET Core.
  • Constructed a filtering system that could handle more than 15 filters and filter sets at a time without adding a big performance cost.
Technologies: ECMAScript (ES6), Web, React, JavaScript, .NET Core, .NET

Voice Interactive Podcasts

I built two proof-of-concept applications allowing podcasters to define interactions over their existing audio tracks. Afterwards, listeners could interact with those defined polls and leave comments along those tracks using only their voice, creating an interaction that does not require visual attention. The paltform was built using React Native, ReactJS and Firebase Firestore.

Team Socializing Platform

I built a web application proof of concept that allowed the members of a larger department to interact with each other and get to know each other on a more personal level. I used Next.js and Firebase to quickly develop a started feature set. I also used Firebase's cloud functions for features like automatic background image resizing.

Online Virtual Classroom Application

I built an application that allowed a teacher to simulate a blackboard within a class using HTML Canvas, and live stream his drawings/writing to the entire class. I built the live stream using WebRTC P2P video streaming which allowed the actual data stream to not have to pass through a media server that I owned. I also implemented a live chat using Firebase.


JavaScript, ECMAScript (ES6), HTML5, CSS, SCSS, HTML, CSS3


React Native, Next.js, Express.js, .NET, .NET Core, Material UI


React, Node.js, REST APIs


Firebase, iOS, Android, Web, MacOS, AWS Lambda


Hybrid Apps, Lambda Functions, Data Processing


WebStorm, Git, Mongoose


Agile, Object-oriented Programming (OOP)


MongoDB, PostgreSQL, Databases, Amazon S3 (AWS S3)

2015 - 2018

Bachelor's Degree in Computer Science

Babeș-Bolyai University - Cluj-Napoca, Romania

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