Sergey Bershadsky, Developer in Bat Yam, Israel

Sergey Bershadsky

Back-end Developer

Bat Yam, Israel
Toptal Member Since
June 19, 2014

Sergey is an accomplished back-end developer with extensive experience in Python, Django, and Cloud DevOps. As a dedicated technology mentor, Sergey has successfully implemented flexible cloud infrastructure, automated testing, and CI, driving team productivity to new heights. He approaches new IT challenges fearlessly and always strives to find innovative solutions that push the boundaries of what's possible in the industry.

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Zoetis - Main
Django, Python, React, Azure, GitHub, Back-end, Docker, Kubernetes, PostgreSQL...
Elasticsearch, Python, JavaScript, React, Django, PostgreSQL, Kubernetes...
Python, Django, Flask, Back-end, Terraform, Docker, Kubernetes, PostgreSQL...


Bat Yam, Israel



Preferred Environment

Amazon Web Services (AWS), Python, Google Cloud Platform (GCP), Django, Infrastructure as Code (IaC), Kubernetes, ELK (Elastic Stack), MongoDB, Solution Architecture

The most amazing...

...things I've developed is a medical appointment application serving 15 million people monthly. I also constructed an MVP that raised $15 million in Y Combinator.

Work Experience

2022 - 2023

Full-Stack and Django Developer

Zoetis - Main
  • Refactored legacy data pipelines into a more strict and clear approach, wrapping data handlers with Schemas as primary contracts.
  • Provided 100% coverage for all newly implemented data pipelines.
  • Migrated similar application features into standalone Django applications. With safe migrations and refactored internal source code, the refactoring touched more than 200 files without breaking any previously implemented features.
  • Provided full knowledge transfer, architecture discovery, and roadmap proposals for refactoring and solution improvements.
Technologies: Django, Python, React, Azure, GitHub, Back-end, Docker, Kubernetes, PostgreSQL, RESTful Web Services, ETL, Tailwind CSS
2020 - 2022

Elasticsearch, Django, and Flask Developer

  • 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, Django, PostgreSQL, Kubernetes, Argo CD, Scrapy, Search, APIs, FastAPI, Docker, OCR, REST, Relational Databases, Containers, Web Scraping, HTML, CSS, Full-stack, Web Development, Node.js, CI/CD Pipelines, Databases, Containerization, Flask, GitHub, Back-end, RESTful Web Services, ETL, Amazon S3 (AWS S3), Selenium, Puppeteer, Tailwind CSS
2021 - 2021

Python Developer

  • Provided full knowledge transfer of the solution.
  • Prepared optimization plan for saving up to 75% of expenses in AWS.
  • Provided new architecture refactoring for AWS EB to Kubernetes with autoscaling features.
  • Implemented pre-commits and full SDLC process with all Django-based services.
  • Prepared best practice documentation for the internal team and performed internal training sessions for developers and the DevOps team.
Technologies: Python, Django, Flask, Back-end, Terraform, Docker, Kubernetes, PostgreSQL, RESTful Web Services, Amazon S3 (AWS S3), Stripe
2020 - 2021

Senior Python/Django Developer

Kizen Technologies, Inc.
  • Fully transferred the knowledge regarding the CRM system that was worked on.
  • Implemented User Audit logging subsystem with neat integration into all apps and legacy state software.
  • Provided full test coverage to all delivered features with Django unit tests.
  • Provided full project review and bug highlighting during initial discovery. Proposed improvement backlog.
Technologies: Python, Django REST Framework, Django, PostgreSQL, Teamwork, GitHub, Back-end, Docker, Kubernetes, RESTful Web Services, Project Management & Work Tracking Tools, SendGrid, Stripe, Next.js
2020 - 2020

Python Developer

Aurora Labs S. A.
  • Implemented IDEX CC exchange market integration with HummingBot.
  • Implemented the most sensitive and performance-dependent parts with Cython.
  • Implemented Integration test suites and delivered full documentation.
Technologies: Python, Financial APIs, Cryptocurrency, Cython, Algorithms, Hummingbot, Back-end, Docker, PostgreSQL, RESTful Web Services, ETL, Stripe
2019 - 2020

Senior DevOps and Elasticsearch Engineer

patent seekers limited
  • 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 Elastic Container Service (Amazon ECS), Docker, Kubernetes, Terraform, Ansible, REST APIs, APIs, PostgreSQL, AWS DevOps, Slack API, Google Calendar API, API Integration, REST, Containers, Location Services and Maps, HTML, CSS, Full-stack, Web Development, FastAPI, CI/CD Pipelines, Databases, Containerization, Back-end, RESTful Web Services, Project Management & Work Tracking Tools, Amazon S3 (AWS S3), Selenium
2018 - 2018

Lead Software Developer

Datazio LLC
  • Implemented data flow engine on top of YAML and Jinja template engine.
  • Wrapped with Kubernetes configuration files and provided secure secrets storage with SOPS.
  • Deployed onto the Google Cloud environment using Managed Kubernetes service.
  • Implemented Client Dashboard for managing, debugging, and overviewing running tasks.
Technologies: Python, Docker, Relational Database Services (RDS), Lambda Functions, Amazon Simple Queue Service (SQS), API Gateways, Tableau, Tableau Server, Reports, BI Reports, PDF, RESTful Web Services, Scrapy, Amazon S3 (AWS S3), Selenium, Puppeteer, Tailwind CSS, SendGrid, Stripe, Auth0, Heroku
2017 - 2018

Lead Back-end Developer and Technology Evangelist

  • Developed back-end microservices architecture using mostly Python and Go.
  • Implemented a JSON-RPC API gateway with Swagger doumentation.
  • 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, HTML, JavaScript, CSS, Architecture, Team Leadership, Full-stack, Web Development, Node.js, CI/CD Pipelines, Databases, Containerization, Flask, Django, GitHub, Back-end, Terraform, Kubernetes, PostgreSQL, RESTful Web Services, Auth0
2015 - 2018

Lead Developer and Technology Evangelist

UMIAS Medicare
  • Developed over 40 API microservices in MSOA style.
  • Developed several modules of the mobile app built with React Native both for iOS and Android.
  • Developed a dedicated independent cluster on HC Consule.
  • Configured an Elastic Search cluster for log analysis in a dedicated environment.
  • Developed a database for a tech support neural network.
  • Developed legacy Docker cluster serving over 200 containers.
  • Developed infrastructure that serves more than 1,200,000 doctor appointments per month.
  • Mentored a team of ten developers in a technical team.
  • Developed several modules of the mobile app built on React Native both for iOS and Android.
  • Implemented Identity provider on top of OAuth 2.0 with Django as Backend.
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, HTML, JavaScript, CSS, Architecture, Team Leadership, Full-stack, Web Development, CI/CD Pipelines, Databases, Containerization, Flask, GitHub, Back-end, Terraform, PostgreSQL, RESTful Web Services, Scrapy
2013 - 2015

Back-end Developer

Mobile Social Network (SAS, Ltd.)
  • Implemented more than 40 services using mostly Python.
  • 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.
  • Provided migration data pipelines from previously implemented services on top of PHP.
Technologies: MySQL, Django, Python, REST APIs, APIs, API/Services Architecture, HTML, JavaScript, CSS, Team Leadership, Full-stack, Web Development, Databases, Containerization, Back-end, Docker, PostgreSQL, RESTful Web Services


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 select and updating queries with one line of Python. I created it using only Python expressions. This library implements 100% of python magic showing my deep knowledge in language.

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.



HTML, HTML5, JavaScript, Python, CSS, SQL, Go, C, Java, C#


Django REST Framework, React Native, Flask, Django, Scrapy, Selenium, Angular, Redux, Tailwind CSS, Next.js


Python Asyncio, React, Emmet, REST APIs, Slack API, Puppeteer, AngularUI, Google API, VK API, Facebook API, Gevent, Fabric, Google Calendar API, Node.js, Stripe


Terraform, Jenkins, Kibana, Zen Coding, GitHub, Ansible, Pytest, Auth0, Bitbucket, GitLab, POV-Ray, Adobe Photoshop, PyCharm, WebStorm, PhpStorm, Maya, AWS SDK, AWS CloudFormation, Apache Airflow, SendGrid, JetBrains, Git, ELK (Elastic Stack), Amazon Elastic Container Service (Amazon ECS), GitLab CI/CD, Amazon Simple Queue Service (SQS), Tableau


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


OpenStack, Kubernetes, Amazon Web Services (AWS), Ubuntu Linux, FreeBSD, Linux, Docker, MacOS, Unix, iOS, Android, Google Cloud Platform (GCP), Azure, Heroku


Relational Databases, Database Security, Docker Cloud, Elasticsearch, PostgreSQL, MySQL, NoSQL, MongoDB, Memcached, Google Cloud, Database Performance, Amazon DynamoDB, Databases, Amazon S3 (AWS S3), Couchbase, Neo4j


Teamwork, Back-end, eCommerce, Back-end Development, Multithreading, APIs, AWS DevOps, FastAPI, Containers, Scraping, Web Scraping, Architecture, Web Development, RESTful Web Services, Project Management & Work Tracking Tools, Algorithms, Customer Relationship Management (CRM), General Medicine, Ubuntu Server, Tornadoweb, Clustering, NixOS, API Integration, Location Services and Maps, Team Leadership, Full-stack, Containerization, CI/CD Pipelines, Argo CD, Search, OCR, Infrastructure as Code (IaC), Solution Architecture, Engineering, Mathematics, Psychology, Pedagogy, English, Economics, Finance, Human Resources (HR), Arabic-English Translation, Libraries, Financial APIs, Cryptocurrency, Cython, Hummingbot, Relational Database Services (RDS), Lambda Functions, API Gateways, Tableau Server, Reports, BI Reports, PDF


2007 - 2011

Master's Degree in Agriculture Management and Economics

MSAU - Moscow

2003 - 2007

Bachelor's Degree in Agriculture Engineering and Education

MSAU - Moscow

2001 - 2003

Translator's Degree in Arabic Languages

Ministry of Foreign Affairs - Moscow