Catalin Oancea, Developer in London, United Kingdom
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Catalin Oancea

Verified Expert  in Engineering

Python Developer

Location
London, United Kingdom
Toptal Member Since
May 17, 2019

Catalin has over seven years of experience developing web services using various languages at top companies such as Facebook, Bloomberg, Bolt, and Fitbit. Having worked as a production engineer at Facebook, his site reliability engineering skills enable him to design and build production-ready services that scale. Catalin's worked mostly in fast-paced teams distributed around the globe, where he has proven to be an excellent communicator.

Portfolio

Vision Marker Ltd
APIs, Python, Amazon S3 (AWS S3), Amazon Web Services (AWS)...
William Pratt
Python, Machine Learning, Stock Trading, Data Visualization...
Bolt
Node.js, TypeScript, React, Amazon S3 (AWS S3)...

Experience

Availability

Full-time

Preferred Environment

Visual Studio Code (VS Code), PyCharm, IntelliJ IDEA, Subversion (SVN), Git, MacOS, Linux

The most amazing...

...project I've worked on was a coding platform designed to sandbox executables and grad submissions from people preparing for their technical interviews.

Work Experience

Python Developer

2024 - PRESENT
Vision Marker Ltd
  • Worked on a platform (co-pilot) that grades UK student responses for national stage exams. It streamlines the entire process, saving educators time and providing accurate results. The system ensures unbiased evaluation of examination papers.
  • Ensured the platform leverages advanced AI and ML to automate the marking process, providing accurate, consistent, and timely results for various questions across different subjects.
  • Created the co-pilot's public-facing API. Used AWS cloud technologies (CloudFormation, Lambda, API Gateway, SNS, SQS, Cognito, DynamoDB, S3, IAM) and handled billing integration with Lago.
  • Refactored and debugged existing code and created the documentation pipeline with Swagger.
Technologies: APIs, Python, Amazon S3 (AWS S3), Amazon Web Services (AWS), Amazon Simple Queue Service (SQS), Azure, Amazon DynamoDB, Amazon Cognito, SDKs, Document Parsing, Microsoft Excel, SQL

Python Developer

2024 - 2024
William Pratt
  • Integrated with trading APIs for fetching market data (Alpha Vantage) and training models based on it.
  • Integrated with Alpaca to place buy/sell orders on NYSE.
  • Worked on improving and trying out different LSTM models to maximise trading profit.
Technologies: Python, Machine Learning, Stock Trading, Data Visualization, Artificial Intelligence (AI), Data Analytics, Stock Exchange, Stock Analysis, Data Science, Alpha Vantage, Alpaca, Microsoft Excel, Pine Script, TradingView, Backtesting Trading Strategies, Trading, SQL, Data Extraction

People-managing Technical Lead

2019 - 2023
Bolt
  • Developed the public API used by restaurants, stores, and shops to integrate directly with Bolt Food. They can now automate the menu (product catalog) and stock updates and manage orders via a push/pull system.
  • Worked on improving the menu system by adding different optimizations and validations. Introduced a sync mechanism between an SQL menu database and an instance of Elasticsearch. The sync is event-based and uses Amazon SNS and Amazon SQS.
  • Managed a team of engineers that worked on the public restaurant API.
Technologies: Node.js, TypeScript, React, Amazon S3 (AWS S3), Amazon Simple Notification Service (Amazon SNS), Amazon Simple Queue Service (SQS), Redshift, Segment.io, Mixpanel, Looker, Spark, MySQL, APIs, Jest, A/B Testing, Test-driven Development (TDD), Maps, Google Maps, Google Maps API, API Integration, Integration, Data Integration, Amazon Web Services (AWS), AWS DevOps, Leadership, Team Leadership, Management, People Management, Technical Leadership, Software Architecture, Product Development, Back-end, Architecture, Distributed Systems, Web Services, Design Patterns, Git, HTML, CSS, REST APIs, API Development, Data Modeling, Solution Architecture, Cloud Services, Full-stack Development, AWS Lambda, JavaScript, Express.js, Python, Agile Software Development, Amazon EC2, Docker, Airtable, Notion, Large Scale Distributed Systems, Parallel Programming, JavaScript 5, JavaScript 6, Inventory Management, Inventory Management Systems, REST, Serverless, PostgreSQL, PostgreSQL 10, GitHub API, OAuth, Encryption, Scalable Web Services, Microsoft Excel, SQL, Data Extraction

AI Engineer

2019 - 2019
Bloomberg LP
  • Contributed to the AI search and relevance group, creating a new algorithm for time-aware named entity disambiguation. The search engine takes into account the world context when performing disambiguation and provides accurate suggestions.
  • Worked on the research part for a few weeks. The research involved analyzing huge amounts of data using Spark and Hadoop to collect ambiguous search queries. It returned a few results to design a new model to fix this.
  • Created a new model that significantly improved the accuracy of query interpretations, from 20% to 86%, in the cases where the query was ambiguous—for example, Amazon fire could be the Amazon product or the fire in the Amazon rain forests.
  • Implemented the prediction function of the model in Python and deployed the newly implemented service in their beta environment, where monitoring and performance analysis were performed.
Technologies: Hadoop, Spark, C++, Solr, Python, Stock Trading, Stock Market, Stock Exchange, Stock Analysis, TypeScript, Automation, Node.js, APIs, Flask, Software Architecture, Product Development, Back-end, Architecture, Distributed Systems, Web Services, Design Patterns, Git, REST APIs, Data Modeling, Solution Architecture, Cloud Services, Full-stack Development, Machine Learning, Agile Software Development, Artificial Intelligence (AI), Neural Networks, Large Scale Distributed Systems, Parallel Programming, REST, Serverless, Algorithmic Trading, PostgreSQL, GitHub API, OAuth, Scalable Web Services, Microsoft Excel, TradingView, Go, Trading, SQL, Data Extraction

Software Engineer

2017 - 2019
Fitbit, Inc.
  • Took part in the architecture review group for a Fitbit internal platform that exposes core Fitbit metrics, such as steps, calories, active minutes, etc., to other internal services.
  • Designed and built large parts of this internal platform using technologies like Node.js, Cassandra, Kafka, Python, Bash, Thrift, and HTTP for communication.
  • Worked on the development of this platform using mainly TypeScript and Node.js.
  • Mentored two part-time engineers and helped them stay on track with their tasks while making sure they have plenty of new learning opportunities.
  • Took part in the process of introducing Node.js in the company and helped developer productivity teams with boilerplate code and documentation to bring Node.js support on par with the existing languages that were in use in Fitbit.
Technologies: Linkerd, Docker, Apache Aurora, Mesos, Apache ZooKeeper, Apache Thrift, Apache Cassandra, Apache Kafka, Java, React, TypeScript, Express.js, Node.js, Heroku, MEAN Stack, Amazon Web Services (AWS), AWS DevOps, DevOps, Health, Healthcare IT, JavaScript, NestJS, APIs, OAuth 2, Team Leadership, Technical Leadership, Software Architecture, Back-end, Fitbit API, Architecture, Distributed Systems, Web Services, Design Patterns, Git, HTML, CSS, REST APIs, API Development, Data Modeling, Solution Architecture, Cloud Services, Full-stack Development, Python, Cassandra, Agile Software Development, MySQL, MongoDB, Integration, API Integration, Google App Engine, Amazon Simple Email Service (SES), Facebook Login, jQuery, Large Scale Distributed Systems, Google APIs, Parallel Programming, JavaScript 6, REST, Serverless, Full-stack, OAuth, Encryption, Scalable Web Services, Google Cloud Platform (GCP)

Production Engineer

2016 - 2016
Facebook, Inc.
  • Worked in the data center management and escalations team developing escalation tools.
  • Used Python, Hack, Thrift, and React to develop a manual escalation tool—back end plus admin dashboard.
  • Improved the usability of their existing tools and automated some escalation procedures.
  • Created a management system to add on-call teams and rotations that worked as a provider system for the escalation service.
  • Took part in design meetings and discussed ideas about performance improvements and scalability.
Technologies: React, Apache Cassandra, Apache Thrift, HHVM, Bash, Hack, Python, NestJS, Express.js, DevOps, AWS DevOps, TypeScript, Algorithms, Software Architecture, Back-end, Architecture, Distributed Systems, Web Services, Design Patterns, Git, REST APIs, Solution Architecture, Cloud Services, Full-stack Development, Agile Software Development, Facebook API, MySQL, Integration, API Integration, Facebook Ads API, Large Scale Distributed Systems, REST, Full-stack, OAuth, Scalable Web Services, Go

Software Engineer

2014 - 2015
Bookster
  • Took part in the development of a recommender system. Used Apache Mahout and Java to implement complex machine learning algorithms.
  • Developed back-end tools in C# for providing business people with consumer insights.
  • Took part in the service language migration process, migrating code written in PHP to C#.
  • Improved the admin dashboard by replacing jQuery with AngularJS.
  • Created an internal calendar-like tool used by employees and by the management to request and approve time off.
Technologies: React, Angular, MySQL, Mahout, Java, PHP, C#, Software Architecture, Back-end, Distributed Systems, Web Services, Design Patterns, Git, HTML, CSS, Full-stack Development, JavaScript, Node.js, Agile Software Development, Flask, Facebook API, Amazon EC2, Integration, API Integration, Amazon S3 (AWS S3), Large Scale Distributed Systems, REST, Full-stack, Blockchain

Bolt Food Public API

I designed and built the public Bolt Food API so that vendors (restaurants, POS companies, and restaurant chains like McDonald's and KFC) can directly integrate their systems with Bolt Food. The API enables them to update menus and manage customer orders in real-time.

The public API is used by thousands of restaurants across tens of countries.

Bloomberg News Search Query Disambiguation

https://www.youtube.com/watch?v=ZyOcrzFsb00
A new model that helps to pick the right interpretation of a search query. This project was completed while working in the AI News Search team at Bloomberg, and it helped by improving the search results relevancy (by correctly tagging the search query).

Bloomberg customers (businesses, governments, philanthropic organizations, etc.) conduct millions of news searches every day. They are looking for close to real-time news and information about companies and investment vehicles. Bloomberg's information retrieval and NLP systems help clients discover the right information they need.

AI Copilot for Exam Grading

https://vision-marker.com
I contributed to the development of an AI exam marking platform. The Co-Pilot for Marking streamlines the entire process, saving educators time and providing accurate results. The system ensures unbiased evaluation of examination papers, eliminating partiality or individual inclinations of markers.

The platform leverages advanced AI and machine learning to automate the marking process, providing accurate, consistent, and timely results for various questions across different subjects.

I created the public-facing API of the Co-Pilot. I used AWS Cloud technologies (CloudFormation, Lambda, API Gateway, SNS, SQS, Cognito, DynamoDB, S3, IAM), handled billing integration with Lago, refactored and debugged existing code, and created the documentation pipeline (Swagger).
2013 - 2017

Bachelor's Degree in Computer Science and Engineering

Politehnica University of Bucharest - Bucharest, Romania

JULY 2019 - PRESENT

Improving Deep Neural Networks: Hyperparameter tuning, Regularization and Optimization

deeplearning.ai

JULY 2019 - PRESENT

Structuring Machine Learning Projects

deeplearning.ai

JULY 2019 - PRESENT

Neural Networks and Deep Learning

deeplearning.ai

FEBRUARY 2019 - PRESENT

Advanced Python

LinkedIn

FEBRUARY 2019 - PRESENT

Python - Data Analysis

LinkedIn

JUNE 2013 - PRESENT

Microsoft Technology Associate - Security

Microsoft

JUNE 2013 - PRESENT

Microsoft Technology Associate - Database Administration

Microsoft

Libraries/APIs

Node.js, jQuery, Fitbit API, REST APIs, API Development, GitHub API, React, Socket.IO, Facebook API, Facebook Login, Facebook Ads API, Google APIs, Mahout, Segment.io, Google Maps, Google Maps API, Python API, SciPy, PySpark

Tools

Amazon Simple Email Service (SES), Git, Notion, Microsoft Excel, Subversion (SVN), IntelliJ IDEA, PyCharm, Apache ZooKeeper, Mesos, Apache Aurora, Solr, Amazon Simple Notification Service (Amazon SNS), Amazon Simple Queue Service (SQS), Looker, Jupyter, Amazon Cognito, AWS CloudFormation, Amazon CloudWatch, AWS IAM, AWS CLI

Frameworks

Express.js, Flask, Apache Thrift, Angular, Spark, Hadoop, Jest, NestJS, OAuth 2, Django, AWS Serverless Application Model (AWS SAM), Swagger

Languages

TypeScript, Python, JavaScript, HTML, Go, SQL, C#, Java, CSS, Pine Script, PHP, Hack, Bash, C++, JavaScript 5, JavaScript 6, Python 3

Paradigms

Agile Software Development, MEAN Stack, REST, Parallel Programming, Design Patterns, Test-driven Development (TDD), DevOps, Automation, Management, Lambda Architecture, Data Science

Platforms

Apache Kafka, Google App Engine, Amazon EC2, Docker, Amazon Web Services (AWS), Linux, MacOS, Mixpanel, Heroku, Visual Studio Code (VS Code), AWS Lambda, Jupyter Notebook, Azure, Blockchain, Google Cloud Platform (GCP)

Storage

Amazon S3 (AWS S3), MySQL, PostgreSQL, MongoDB, Cassandra, Redshift, Data Integration, HDFS, PostgreSQL 10, Amazon DynamoDB, Databases, Microsoft SQL Server

Other

Distributed Systems, APIs, API Integration, Integration, Algorithms, Software Architecture, Back-end, Architecture, Web Services, Solution Architecture, Data Modeling, Cloud Services, Full-stack Development, Airtable, Full-stack, OAuth, Scalable Web Services, Document Parsing, Trading, Large Scale Distributed Systems, Machine Learning, Artificial Intelligence (AI), Neural Networks, Leadership, Team Leadership, People Management, Data Structures, Technical Leadership, Product Development, Serverless, Algorithmic Trading, Encryption, TradingView, Backtesting Trading Strategies, Data Extraction, HHVM, Apache Cassandra, Linkerd, A/B Testing, Maps, AWS DevOps, Health, Healthcare IT, Stock Trading, Stock Market, Stock Exchange, Stock Analysis, Deep Learning, Inventory Management, Inventory Management Systems, Amazon Fire TV, SDKs, Forums & Social Networking Portals, Lambda Functions, Billing, AI Model Intergration, OpenAI GPT-4 API, Generative Pre-trained Transformers (GPT), Llama 2, OpenAI, Data Visualization, Data Analytics, Alpha Vantage, Alpaca

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