Serge Ponomarov, Developer in London, United Kingdom
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Serge Ponomarov

Verified Expert  in Engineering

Web Developer

Location
London, United Kingdom
Toptal Member Since
November 29, 2013

Serge is a senior software engineer who has built massive web applications from scratch and designed complex back-end architecture to withstand high loads. He has worked remotely on a full-time basis with clients, primarily from the US and Canada across various industries, including eCommerce, blockchain, and education.

Portfolio

Toptal Clients
Amazon Web Services (AWS), Yii, PHP, REST APIs, SQL, Ubuntu, JavaScript, NGINX...
GoCardless
Ruby, Ruby on Rails (RoR), Google Cloud, PostgreSQL, Prometheus, Grafana...
CommerceHQ
PayPal, Stripe, OAuth, Agile, Continuous Integration (CI), Sentry, Caching, DNS...

Experience

Availability

Part-time

Preferred Environment

Slack, Jira, Git, MacOS, Visual Studio Code (VS Code), Sentry, Grafana, Kibana, Zsh

The most amazing...

...thing I've built from scratch is a distributed eCommerce platform that now processes seven-digit monthly revenues across thousands of stores.

Work Experience

Senior Software Engineer

2013 - PRESENT
Toptal Clients
  • Worked for clients as part of a network of top-tier remote software developers that accepts only the top 3% of freelance talent.
  • Served mainly US and Canadian clients across industries such as eCommerce, construction, publishing, education, automobiles, and music.
  • Completed a long-term client engagement that lasted over five years.
Technologies: Amazon Web Services (AWS), Yii, PHP, REST APIs, SQL, Ubuntu, JavaScript, NGINX, Google Cloud

Software Development Engineer III

2022 - 2023
GoCardless
  • Worked in a team responsible for building and maintaining banking integrations in a fintech unicorn that processes over $30 billion of payments annually across more than 30 countries.
  • Extracted business logic from our monolith app into microservices to help achieve our scalability goal of handling 16 million payments per day.
  • Rebuilt a complex database query with many joins from the ground up using a denormalized partitioned table, taking it from 25 minutes to 1.5 seconds, achieving a 99.9% improvement.
  • Led a project that enabled us to run payment submission pipelines in different time zones, increasing our competitiveness in foreign markets.
  • Performed code reviews actively and mentored new hires.
Technologies: Ruby, Ruby on Rails (RoR), Google Cloud, PostgreSQL, Prometheus, Grafana, Kibana, Distributed Systems

Senior Back-end Developer

2015 - 2022
CommerceHQ
  • Built the back end from scratch for an eCommerce platform similar to Shopify that now processes 7-digit revenues monthly across thousands of stores. My code handled over $100 million worth of checkouts in total.
  • Devised a robust architecture for high loads, where customers’ stores can be quickly moved across servers thanks to our own DNS setup.
  • Developed systems on my own that whole companies would build, such as a customer support system with MongoDB and WebSockets.
  • Integrated over a dozen third-party APIs into our platform and built our own REST API that's open to others.
  • Worked remotely with a small team of awesome people that competed with giants like Shopify, and met with them on company retreats across Europe.
Technologies: PayPal, Stripe, OAuth, Agile, Continuous Integration (CI), Sentry, Caching, DNS, SSL, GitHub, TeamCity, Notion, Jira, Confluence, REST, NGINX, MongoDB, WebSockets, Redis, PostgreSQL, MySQL, Linode, Ubuntu, Yii, PHP, REST APIs, Model View Controller (MVC), Object-oriented Programming (OOP), Webhooks, Stripe API, DevOps

CommerceHQ

https://commercehq.com/
A high-load, high converting eCommerce platform.

I was the first engineer and started the development from scratch. I've been working on it for five years, and I'm truly proud of what we've built as a team.

ZenFuse

https://zenfuse.io/
A cryptocurrency trading platform that has built-in connectivity to major exchanges.

I built the minimum viable product (a back-end REST API) for this blockchain startup that went on to a successful fundraise.

Wine Pairing App

https://epic-poitras-73d63f.netlify.app/
An app that helps users find the best food and wine pairings.

I built this as a fun personal project to use during the 2020 COVID-19 lockdown days and to brush up on my front-end development skills in JavaScript and Vue.js.

Toptal React Academy

https://vimeo.com/toptal/review/505888912/c4bbb5999f?utm_medium=email
The Toptal React Academy is an exclusive learning program that teaches the React framework to select members of the Toptal network. After a month of study, all graduates are tasked with completing a 30-40 hour final project to build and deliver a React app from scratch.

Languages

HTML, PHP, Ruby, CSS, SQL, CSS3, JavaScript, HTML5, GraphQL, ECMAScript (ES6), Sass, Python

Frameworks

Yii, Ruby on Rails (RoR), Express.js, Bootstrap, Redux, OAuth 2

Libraries/APIs

REST APIs, Stripe API, Vue, Node.js, React, Stripe, Context API, Twilio API, Facebook API, PayPal API, jQuery

Paradigms

REST, Model View Controller (MVC), Object-oriented Programming (OOP), DevOps, Agile Software Development, Continuous Integration (CI), Agile

Other

Webhooks, PayPal, Distributed Systems, APIs, API Integration, SSL, DNS, OAuth, VCS, Ajax, WebSockets, Caching, Apollo, Axios, Cloudflare, Prometheus, CI/CD Pipelines

Tools

PhpStorm, Git, TeamCity, Jira, Slack, Composer, NGINX, Confluence, Notion, GitHub, Sentry, NPM, RabbitMQ, Stripe Checkout, Grafana, Kibana, Zsh

Platforms

Ubuntu, MacOS, Amazon Web Services (AWS), OS X, Linode, Firebase, Heroku, Netlify, Visual Studio Code (VS Code), Google Cloud Platform (GCP)

Storage

PostgreSQL, Amazon S3 (AWS S3), MySQL, Redis, MongoDB, Google Cloud

NOVEMBER 2020 - PRESENT

Toptal React Academy Graduate

Toptal, LLC

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