Sergey Bershadsky, Back-end Developer in Bat Yam, Israel
Sergey Bershadsky

Back-end Developer in Bat Yam, Israel

Member since June 19, 2014
Sergey is an experienced back-end developer. He's been a front-end developer in the past and even a designer and musician. Lately, he's done a lot of DevOps and tech-related mentorship. He brings flexible cloud infrastructure auto-testing and CI, boosting team productivity. His life motto is to not be afraid to face new IT challenges.
Sergey is now available for hire


  • AppDirect
    Elasticsearch, Python, JavaScript, React, Flask, Django, PostgreSQL...
  • Toptal Clients
    Amazon Web Services (AWS), GitLab CI/CD...
  • Play2Live
    Amazon Web Services (AWS), React Native, React, Google Cloud, Docker, Python...



Bat Yam, Israel



Preferred Environment

Amazon Web Services (AWS), Python, Git, JetBrains, Linux, Back-end

The most amazing...

...project I've developed is a medical appointment system that serves one million patients per month.


  • Elasticsearch, Django, and Flask Developer

    2020 - 2022
    • Developed a web application that provides the ability to search throughout the entirety of the web application with minimal integration effort.
    • Built a universal search scraper that extracts text from dynamic SPA, PDF, Office Docs, and even images using OCR.
    • Delivered the services using Docker, Docker Compose, and Kubernetes configurations. Documented it all well for future developers.
    • Implemented the API using the Django REST framework (DRF) and FastAPI libraries.
    • Developed a standalone application that provides secure and categorized storage of files, as well as a catalog feature for storing documentation.
    Technologies: Elasticsearch, Python, JavaScript, React, Flask, Django, PostgreSQL, Kubernetes, Argo CD, Scrapy, Search, APIs, FastAPI, Docker, OCR, REST, Relational Databases, Containers, Web Scraping
  • Senior DevOps and Elasticsearch Engineer

    2019 - 2020
    Toptal Clients
    • Implemented a full AWS cloud provisioning with Terraform throughout three separate environments (development, staging, and production).
    • Implemented flexible Elasticsearch cluster configuration with Terraform and a maintenance toolset integrated with AWS infrastructure with Ansible. This configuration gives the ability to build any topology Elasticsearch cluster in minutes.
    • Performed full-featured Kubernetes cluster Terraform configuration. The configuration includes integration with AWS EBS volumes, ALB, and CloudWatch. Also, it has an autoscale feature and OpenVPN access on per cluster bases.
    • Implemented a full CI/CD pipeline with GitLab and AWS infrastructure. Testing, building, and delivery were fully automated.
    Technologies: Amazon Web Services (AWS), GitLab CI/CD, Amazon ECS (Amazon Elastic Container Service), Docker, Kubernetes, Terraform, Ansible, REST APIs, APIs, PostgreSQL, AWS DevOps, Slack API, Google Calendar API, API Integration, REST, Containers, Location Services and Maps
  • Lead Back-end Developer and Technology Evangelist

    2017 - 2018
    • Developed back-end microservices architecture using mostly Python and Go.
    • Implemented a JSON-RPC API gateway.
    • Created deployment proposals and base CI/CD pipelines and tools.
    • Developed a multi-layer authorization system on top of the JWT.
    • Integrated BitShares blockchain into financial sub-system.
    • Integrated TenderMint blockchain self-hosted private network for financial and event tracking.
    Technologies: Amazon Web Services (AWS), React Native, React, Google Cloud, Docker, Python, REST APIs, APIs, API/Services Architecture, REST, Containers
  • Lead Developer and Technology Evangelist

    2015 - 2018
    UMIAS Medicare
    • Developed over 40 API microservices in SOA style.
    • Developed web security infrastructure analysis.
    • Developed several modules of the mobile app built with React Native both for iOS and Android.
    • Developed a DC independent cluster.
    • Configured an ELK cluster for log analysis.
    • Developed a database for a tech support neural network.
    • Developed a Docker cluster serving over 200 containers.
    • Developed infrastructure that serves more than 1,200,000 doctor appointments per month.
    • Mentored around ten people in a technical team.
    • Developed several modules of the mobile app built on React Native both for iOS and Android.
    • Developed private networking integrated with Django services authentication and SSO with internal/external services.
    Technologies: React, React Native, Android, iOS, ELK (Elastic Stack), SQL, MySQL, Django, Python, Docker, Ansible, Linux, REST APIs, APIs, API/Services Architecture, REST, Containers, Location Services and Maps, Web Scraping
  • Back-end Developer

    2013 - 2015
    Mobile Social Network (SAS, Ltd.)
    • Created more than 40 social features.
    • Developed a fast messaging system handling 1B user messages.
    • Built a Twitter-like following feature using a custom incremental indexing system.
    • Created a file uploading feature by file conversion using FFmpeg and ImageMagick. Stored every file uploaded by users in different formats.
    • Developed SMS and email messaging functionality through Django/Celery.
    • Implemented silent two-phase deployment (supervisor with Nginx) so that users don't notice when the site updates.
    • Handled 2.5 million registered users with 15,000 online each evening. Generated around 60TB of storage user file data.
    • Worked on a two-person team with the front-end developer.
    Technologies: MySQL, Django, Python, REST APIs, APIs, API/Services Architecture
  • Senior Developer

    2010 - 2013
    Online Farm-like Game (SAS, Ltd.)
    • Divided the project amongst four developers (game designer, art designer, back-end developer, and front-end developer).
    • Created a fast REST protocol and implemented game logic. Created around 200 REST nodes as a result, with twenty functional elements per node.
    • Created a REST-oriented gaming solution with two front-ends for smartphones and an extremely simple WAP version with base gaming features.
    • Handled a maximum of 10,000 users at a time, with over 250,000 users registered in the first three months after launch.
    • Used MongoDB and Memcached for the main storage.
    • Wrote the back-end application server in Python on top of Gevent.
    • Built two front-ends to work on top of Gevent+Flask.
    • Published the game in popular social networks (VK, Mail, Odnoklassniki) and in a mobile app catalog.
    • Implemented many cool social features such as messaging, forum, support, social groups, and game quests among users.
    • Included around twenty mini-games such as individual quests, fishing, and tasks related to plants and animals.
    • Incorporated around 400 game items created by the art designer.
    Technologies: Django, Python
  • Web Developer

    2008 - 2010
    Online Shopping Cart System (Esmeralda, Ltd.)
    • Worked in a team of five developers.
    • Handled over 250,000 registered users (around 1,000 users at any given time).
    • Integrated third-party accounting system 1C:Enterprise through a RESTful service built on top of Django/TastyPie.
    • Created over thirty new Django modules within project.
    • Built thirteen shop views, delivering retail and wholesale product information and a shopping-cart feature, based on single platform (Django). Included authorization for all sites through popular social networks like Facebook, VK, and more.
    • Implemented a single sign-on (SSO) feature across all sites.
    • Implemented a simple CMS page-tree feature, RTE, and functionality for turning pluggable product info directly into text.
    • Implemented all background tasks using the Django/Celery module.
    Technologies: Memcached, MongoDB, MySQL, Django, Python


  • React Native Yelp-like MVP App

    The task was in a short cycle to create a working prototype of a Yelp-like application with per-person granularity. I was using the Google Cloud Engine. Initial provisioning was done with Ansible. React Native App both for iOS and Android was developed. Mobile app features included geolocation service, authentication and resource management. Docker deployment on GKE with MySQL Cloud as data storage. The back-end was done with Python (Django with DRF). There was one mobile application that interacts with the back-end through a REST API built with React Native. The facility manager's dashboard was built with Django using a Material Design look. The goal was achieved.

  • React Native Healthcare App

    Developed React Native-based authorization components for a UMIAS project. The authentication service is built on top of JWT and the back-end is built with Django/python. The most challenging part was creating encrypted user storage with a multikey recovery feature.

  • Python/Django/MySQL - Social Network

    I created the back-end for this social network. I also implemented features for fast and extendable messaging, content sharing, and file uploading with a converter to suitable formats. It integrates the OAuth API for third-party site functionality for creating accounts using social networks. It also features fast CMC registration and a powerful but simple anti-spam integral scoring system. For storage, I used MySQL, but for complex selections, I used caching and indexing through Memcached, Xapian, or custom-written indexes. Everything is built on top of Django with i10n in mind.

  • Python/Flask/Gevent/MongoDB, Farm-like Online Game

    I wrote the back-end for this game as a fully REST application. Every action in the game was declared in an API with MongoDB as the storage engine. In game, the user can farm plants, trees, and animals, take quests, fish, and battle with other users using plants and fruits. Also, every user can organize groups among different users and achieve game goals together. The most challenging thing for me was to create a system establishing the game balance in the most simplified way. I used Excel sheets to load code on startup and act as a database, allowing the game designer to simply change parameters in the sheet to establish a new balance.

  • Python/Django/MySQL eCommerce System

    I created the back-end and front-end for a shopping cart system consisting of 13 fully functional sites (wholesale and retail). I wrote a Django application with generic storage for the products, product attributes, and categories. I implemented an SSO feature to stay logged in on every site. I also developed a REST service API that exchanges product info and orders with the accounting system in a bi-directional way. I used MongoDB as a caching system for fast product data access.

  • MongoDB Magic Library

    A simple experimental library for making deep and complex MongoDB selections and updating queries with one line of Python. I created it using only Python expressions.

  • Medicine Unlimited

    I contributed to about 40 TYPO3 projects between 2005 and 2014 along with hundreds of custom extensions, involved in the software development lifecycle from wireframes through to deployment. The most challenging were shop-like systems like the one linked here.


  • Languages

    HTML, HTML5, Python, JavaScript, SQL, Go, C, Java, C#
  • Frameworks

    Django REST Framework, React Native, Flask, Django, Angular, Redux, Scrapy
  • Libraries/APIs

    Python Asyncio, Emmet, REST APIs, Slack API, React, AngularUI, Google API, VK API, Facebook API, Gevent, Fabric, Google Calendar API
  • Tools

    Terraform, Jenkins, Kibana, Zen Coding, GitHub, Ansible, Bitbucket, GitLab, POV-Ray, Adobe Photoshop, PyCharm, WebStorm, PhpStorm, Maya, AWS SDK, AWS CloudFormation, JetBrains, Git, ELK (Elastic Stack), Amazon ECS (Amazon Elastic Container Service), GitLab CI/CD
  • Paradigms

    Object-oriented Programming (OOP), Aspect-oriented Programming, API/Services Architecture, REST, Functional Programming, Concurrent Programming, Object-oriented Design (OOD)
  • Platforms

    OpenStack, Kubernetes, Ubuntu Linux, FreeBSD, Linux, Docker, MacOS, Unix, iOS, Android, Amazon Web Services (AWS)
  • Storage

    Relational Databases, Database Security, Docker Cloud, Elasticsearch, PostgreSQL, MySQL, NoSQL, MongoDB, Memcached, Google Cloud, Database Performance, Amazon DynamoDB, Couchbase, Neo4j
  • Other

    Teamwork, Back-end, eCommerce, Back-end Development, Multithreading, APIs, AWS DevOps, Containers, Scraping, Web Scraping, Algorithms, Customer Relationship Management (CRM), General Medicine, Ubuntu Server, Tornadoweb, Clustering, NixOS, API Integration, Location Services and Maps, Argo CD, Search, FastAPI, OCR


  • Master's Degree in Agriculture Management and Economics
    2007 - 2011
    MSAU - Moscow
  • Bachelor's Degree in Agriculture Engineering and Education
    2003 - 2007
    MSAU - Moscow
  • Translator's Degree in Arabic Languages
    2001 - 2003
    Ministry of Foreign Affairs - Moscow

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