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Cosmin Rusu, Software Developer in Lausanne, Switzerland
Cosmin Rusu

Software Developer in Lausanne, Switzerland

Member since June 23, 2017
Cosmin interned at Amazon and Google, working on high-scalable, distributed systems; working mostly on Java back-end and other small scripts in Python. He is currently working for a startup called Kuende, writing Scala and Go Microservices on top of Google Cloud. Cosmin has a strong background in advanced algorithms and data structures, in C/C++ and is very passionate about machine learning.
Cosmin is now available for hire



  • C++, 4 years
  • JavaScript, 4 years
  • Python, 4 years
  • Ruby on Rails (RoR), 3 years
  • Jupyter Notebook, 1 year
  • React Native, 1 year
  • Scala, 1 year
Lausanne, Switzerland



Preferred Environment

Git, Tensorflow, RoR, Python, Data Science

The most amazing...

...thing I've coded was at my internship with Google, delivering a new type of automatic content creation, containing action moments from user's videos.


  • Stripe Data Consultant

    2019 - PRESENT
    Abundance Digital
    • Answered relevant business questions based on available Stripe data for this community-based company. The answered resembled their subscription model and how well does it perform.
    • Implemented a checkout page to allow people to pay for the yearly subscription on a monthly basis using
    • Implemented relevant SQL Queries in Stripe Sigma so that the business owners can always run the queries on the latest data.
    • Helped to automate their boarding process with Zapier.
    • Extensively analyzed the subscriptions data and suggested ways to improve churn rate, revenue and profit.
    Technologies: Stripe Sigma, Python, Ruby on Rails
  • Software Engineer Intern

    2019 - 2019
    • Researched new approaches to build a request predictor - a time-series discrete value model.
    • The problem resembles Intermittent Demand Forecasting. The approaches considered include Croston's method, Bootstrapping, RNNs and.
    • Implemented and tested the performance of different algorithms on previously acquired data in Python Colab.
    • Implemented the method that performed best in our dataset.
    • Proactively proposed different methods to make the project a success.
    Technologies: Python, C++
  • Software Engineer Intern

    2018 - 2018
    • Built a fully automated machine learning model training and prediction pipeline. This was the first step in moving from alpha testing where we get the predictions manually by running R scripts, to a beta phase.
    • Ensured the data generated by the pipeline is consumed by an internal dashboard. A strong motivating factor for building an automated pipeline is that the data is always updated and will solve the out-of-sync data problem caused by communication delay between the Engineering, Product and Sales teams.
    Technologies: C++, Protocol Buffers, R, Machine Learning, Unix
  • Full Stack Developer

    2018 - 2018
    One Step Software
    • Worked as a full-stack engineer for a sober-living SaaS platform.
    • Built the CI pipeline in order to make sure our service did not introduce any bugs.
    • Collaborated with the team to make our Trello better and advocated for a TDD approach in order to make sure we serve the best software to their clients.
    • Contributed to the Rails web app, introducing new features, implement backlog tasks, and fixing existing bugs.
    • Developed the API for the React Native mobile app and then used that API to build the mobile app.
    Technologies: Ruby on Rails, Heroku, React Native,
  • Back-end Engineer

    2017 - 2018
    • Contributed to microservices for interacting with Google Cloud storage and Google Cloud PubSub.
    • Developed a GoLang gRPC server that interacts with Google Storage.
    • Built a Scala gRPC client that connects to the Go server. The reason for doing this is that Google Storage SDK does not currently support Scala.
    • Wrote unit, integration, and end to end tests.
    Technologies: Scala, GoLang, Ruby on Rails, gRPC
  • Full stack web developer

    2017 - 2017
    NLV Production
    • Contributed to the implementation of new features and fixing bugs for the website.
    • Used Stripe as a payment processor and investigated the problems they were experiencing with customers being charged more.
    • Implemented a new workflow for the admin dashboard that improved the organization's processes.
    • Been very proactive and provided multiple solutions for every problem that the customer was interested in solving.
    • Fixed memory leaks we experienced on the Heroku dyno.
    Technologies: Ruby on Rails, Heroku, PostgreSQL, Sidekiq, Stripe, MailGun
  • Software Engineer Intern

    2017 - 2017
    • Interned in the Google Photos Team. The project involved extending the selection framework for auto-created movies based on user content and implementing a few new concept movies.
    • Created the concept "child friendly" movie. The basic idea is that if we detect that a lot of pictures contain kids, toddlers, or children, we select music that is suitable for a child movie.
    • Designed a second concept movie called 'Outdoor Movie' and it basically tries to match outdoor pictures with suitable outdoor songs.
    • Conceptualized a third movie called 'Highlight Reel' and the main idea is that we want to crop the user's videos so that we retain only some 'action moments'. An action moment is a 5s clip in the movie where we detect some action (i.e. throwing a basketball or shooting a baseball).
    Technologies: Java 8, Protocol Buffers
  • Mobile Developer

    2016 - 2017
    • Contributed to the team that develops the Kuende mobile application (available to download on AppStore and Play Store), a social network based on gamification.
    • Implemented a Trie based algorithm for searching people, a wrapper around a list-view so you can easily declare, add filters and comparators to lists, and other small features.
    • Optimized the way we persist our data so that the information is fast accessible and rendered on the phone.
    • Concepted and implemented the Flux architecture on top of C++ and Qt.
    Technologies: React Native, Javascript, C++, Qt, Qml, Flux, Android, iOS
  • Teacher

    2016 - 2016
    • Taught computer science fundamentals to high-school students through the non-profit organization (
    • Presented advanced algorithms and data structures to students interested in the National Olympiad in Informatics.
    • You can find some of the problems that I solved on various competitive programming challenges can be found here:
    Technologies: Advanced algorithms and data structures in C/C++
  • Software Engineer Intern

    2016 - 2016
    • Interned in the Robot Detection Research Team at Amazon Development Center Iasi.
    • Created a linkage and score system for robotic attributes. The main challenge was the huge amount of nodes and data that had to be processed every day.
    • Contributed to mitigation of all of the robotic activity that crawls our website, with two things in mind. First, we didn't want to block a real user! Second, we wanted to let some friendly bots crawl the website (eg GoogleBot, BingBot).
    • Designed a system that was able to give a score for each incoming request on the website. Then, based on that score we can decide if the current request was made by a human or a robot. For this approach, we split the request into simple attributes such as user agent, IP, customer id and we independently compute the scores for each such attributes. In the end, we can average the scores to get the request score.
    • Computed the scores as a series of Hadoop Map Reduce jobs that ran on Amazon's Hadoop Clusters and infrastructure. I had a lot of freedom with the project and I learned a lot while designing such a scalable, distributed algorithm.
    Technologies: Java, Hadoop, MapReduce, Machine Learning, JavaScript, NodeJs
  • Android Developer

    2013 - 2013
    • Built the e-communio app based on the already built local church news website.
    • Understood the main concepts of Android OS and the process of publishing an app.
    • Created the app as a very simple, and at the core, just a list view, containing the latest news that I parsed from a web service written in C# that connects to the database, gathers the news, and splits a JSON array.
    • On the mobile side, I created a request for the news, parsed them and displayed them. When the user clicked one of the items, it will go to another screen where they could read the entire content of the article. There were other nice features such as increasing and decreasing the size of the text, sharing the article, and additional text effects.
    Technologies: Android


  • Data Analysis Project on DST Impact on Users (Other amazing things)

    I've worked on a data analysis project to understand the impact of daylight saving time impact on web usage around the world.

  • Road Segmentation (Development)

    Worked on building a classifier to segment roads in satellite images.

  • Chatbot (Development)

    Facebook Messenger chatbot that uses the Facebook Messenger codes.

    Scan a QR code in messenger and get different targeting ads/promotions.

  • API Integration (Development)

    I have worked for NXT Spots Inc to integrate two of their services they were using: LeagueApps for their payment processor and Copper for their CMS.

  • Med Prep (Development)

    I've built an online exam for medicine students web application for this client. The stack I used was Ruby on Rails, PostgreSQL, React.js, ActiveAdmin, and Stripe as a payment processor.

    The admin dashboard shows aggregated transactions data.

  • Watersheds Data Visualization (Development)

    I've created a visualization tool for people at Stanford to gain more insights into how different experiments affect watershed metrics.

    Technologies: D3.js, jQuery, HTML, CSS, Bulma

  • Babes-Bolyai University of Cluj-Napoca Courses (Development)

    All my project assignments at university.

    The projects there range from web applications to machine learning, parallel and distributed programming, or even math courses like statistics or linear algebra.

  • (Development)

    I've built a Google Chrome extension that makes it easy to quickly convert date times intent in Gmail and Inbox by Gmail.


  • Languages

    Ruby, C++, Java 8, JavaScript, Python, Scala, SQL, Go, Bash, GraphQL, Hugo, Elixir
  • Frameworks

    Lift, React Native, Ruby on Rails (RoR), Ruby on Rails 5, Qt, Spark, Hadoop, Phoenix
  • Libraries/APIs

    jQuery, React, Ruby on Rails API, D3.js, Facebook API, Facebook Messenger API, NumPy, Pandas, Stripe, Stripe API, Braintree API, TensorFlow, PySpark, Scikit-learn, Matplotlib, SciPy
  • Other

    Algorithms, Data Structures, BrainTree, Leadership, Statistics, Data Analytics
  • Tools

    Trello, IntelliJ IDEA, Jekyll, Scikit-image
  • Paradigms

    Agile Software Development, Scrum, Data Science
  • Platforms

    Jupyter Notebook, Linux, MacOS, Kubernetes
  • Storage

    PostgreSQL, MySQL, AWS S3, Google Cloud


  • Master's degree in Data Science
    2018 - 2020
    EPFL | École polytechnique fédérale de Lausanne - Lausanne, Switzerland
  • Bachelor's degree in Computer Science
    2015 - 2018
    Babes-Bolyai University - Cluj-Napoca
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