Haymi Gulersen Barokas, Developer in Barcelona, Spain
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Haymi Gulersen Barokas

Verified Expert  in Engineering

Full-stack Developer

Location
Barcelona, Spain
Toptal Member Since
September 2, 2022

Haymi is a full-stack developer bringing business vision to life using technology. He has seven years of enterprise experience in industry-leading companies such as Facebook and Coca-Cola, as well as in bootstrapping a startup on the side with limited resources. Aside from his technical proficiency, Haymi pays great attention to clients to understand their ultimate goals and perform his work accordingly.

Portfolio

Sanamekan
React, Next.js, React Native, Node.js, SQL, PostgreSQL, GraphQL, TypeScript...
Monad Inc.
Python 3, Python, Redshift, Pytest, Docker, Kubernetes, SQL, PostgreSQL, React...
Facebook
React, MySQL, SQL, PHP, Debugging, Automation, GraphQL, Flow, HTML, APIs, JSX...

Experience

Availability

Part-time

Preferred Environment

React, React Native, Hack, PHP, JavaScript, Python, GraphQL, SQL, Haskell, Tailwind CSS

The most amazing...

...product I've built is a mobile application in React Native, Node.js, GraphQL, and PostgreSQL as my side project.

Work Experience

Co-founder and Developer

2020 - PRESENT
Sanamekan
  • Developed the iOS and Android mobile apps in React Native to enable people to find extraordinary venues for their events. The back-end stack consisted of Node.js, GraphQL, PostgreSQL, and Meilisearch.
  • Migrated the web application from WordPress to Next.js.
  • Debugged full-stack production issues such as slowness and outdated dependencies.
Technologies: React, Next.js, React Native, Node.js, SQL, PostgreSQL, GraphQL, TypeScript, Tailwind CSS, Socket.IO, WebSockets, REST APIs, HTML, APIs, Figma, Laravel, JSX, JSON Web Tokens (JWT), Responsive Web Apps, Web Development, CSS, Full-stack, Databases, Interviewing, MongoDB, NoSQL, Expo.io, iOS, Apollo, Mobile Applications, Mobile Apps, React Native for Web, Swift, Single-page Applications (SPA), Back-end, Monorepos, Git, Strapi, Mobile Development, Android, Minimum Viable Product (MVP), Front-end, App Store, Express.js, Expo, Jest, Search Engine Optimization (SEO), Zustand, Google Play Console, Object-oriented Programming (OOP)

Full-stack Engineer

2022 - 2024
Monad Inc.
  • Rewrote existing data extraction logic in a highly parallelized manner. Achieved a 2,000 faster extraction overall. Deployed the solution production for the biggest paying customer.
  • Wrote a Databricks integration to extract data from Redshift to Databricks in a scalable manner using Singer and streaming.
  • Participated actively in the on-call rotation and debugged and resolved critical production bugs.
  • Led proofs of concept to migrate a legacy data ingestion model to Apache Spark and structured streaming.
Technologies: Python 3, Python, Redshift, Pytest, Docker, Kubernetes, SQL, PostgreSQL, React, Tailwind CSS, Prefect, Apache Spark, Databases, Data Warehouse Design, ELT, ETL, ETL Testing, Singer ETL, Snowflake, Databricks, Amazon Web Services (AWS), FastAPI, Jest, Zustand, Data Transformation, Object-oriented Programming (OOP)

Full-stack Production Engineer

2021 - 2022
Facebook
  • Contributed to a full-stack internal web application to reduce the operational load for data center employees and orchestrate the lifecycle of servers via automation.
  • Participated in an on-call rotation to mitigate critical production issues as quickly as possible.
  • Met with XFN partners regularly to understand business needs, helped them prioritize by assessing impact vs. effort, and landed features to make them more efficient by reducing manual work.
Technologies: React, MySQL, SQL, PHP, Debugging, Automation, GraphQL, Flow, HTML, APIs, JSX, Web Development, CSS, Full-stack, Databases, Interviewing, Code Review, Technical Hiring, Source Code Review, Task Analysis, Single-page Applications (SPA), Back-end, Monorepos, Git, Minimum Viable Product (MVP), Front-end, Python, Jest, Object-oriented Programming (OOP)

Automation Developer

2017 - 2021
Facebook
  • Identified signals of malicious behavior through data analysis and crafted automation to tackle abuse vectors.
  • Improved internal tools to reduce time spent and to increase quality in human reviews.
  • Acted as a tech lead within the team by mentoring peers in system design, aided in debugging production issues, and connected them with relevant stakeholders to unblock their projects.
  • Built data pipelines to collate data spread out and turned it into actionable insights with data visualization. Enabled business people to build processes around these insights.
Technologies: Haskell, Python, JavaScript, Automation, Data Pipelines, APIs, JSX, Interviewing, Code Review, Technical Hiring, Source Code Review, Task Analysis, Single-page Applications (SPA), Back-end, Git, Minimum Viable Product (MVP), Data Transformation

Business Analyst

2015 - 2017
Coca-Cola
  • Led a project to consolidate five different region-wide instances into a single streamlined tool within Eurasia and Africa, reducing the yearly support costs by 80%.
  • Served as a bridge between businesses and developers by gathering requirements and running user acceptance testing.
  • Oversaw the software support process by tracking key metrics such as turnaround time, resolution time, and quality.
Technologies: Software Project Management, User Acceptance Testing (UAT), Minimum Viable Product (MVP)

React Native App for Sanamekan

A React Native-based mobile app for Sanamekan, my side business, enables users to perform detailed searches and filtering, have real-time chat conversations with venue owners, and receive offers for their events.

I built the whole technical stack, including the back end and front end. For the back end, I used Node.js, PostgreSQL, and Strapi as CMS, and I also implemented Meilisearch, similar to ElasticSearch, to enable rapid search for the users in the app. By leveraging WebSocket, I built real-time features from scratch, such as in-app chat without third-party tools due to a tight budget.

Automation and Data Analysis Project

To reduce harmful activity such as spam on the platform, I built multiple automation rules using Haskell to create a structured dataset that enabled further analyses. I combined this dataset with other signals using Python and SQL to build data pipelines to feed directly into a Tableau dashboard, helping business people to make operational decisions.

I ran sessions with stakeholders to get feedback and then continued iterating on it. Eventually, we built a whole operational flow around this dashboard, reducing the abuse areas we monitored considerably.

Migration of Sanamekan's WordPress Web App to Next.js

I migrated an underperforming WordPress web application to Next.js to benefit from static site generation and more advanced technologies. The process included:
• migrating core WordPress SQL tables to PostgreSQL;
• building the back end in Node.js and the API in GraphQL;
• creating a script to migrate static files such as images into a new server;
• redesigning the look and feel and rewriting the front end in Next.js.

Data Center Web App and Automation

I worked on an internal web app focused on reducing the operational burden for data center employees and an automation engine that dramatically reduced human manual actions. I mainly used React, GraphQL, Hack, and SQL to implement these solutions.

Languages

JavaScript, Python, GraphQL, SQL, TypeScript, Hack, PHP, HTML, CSS, Haskell, Swift, Python 3, Snowflake

Frameworks

React Native, Next.js, Tailwind CSS, JSON Web Tokens (JWT), Selenium, Jest, Laravel, Apache Spark, Express.js

Libraries/APIs

React, Node.js, Socket.IO, REST APIs, MobX, React Native for Web

Tools

Expo.io, Expo, Flow, JSX, Git, NGINX, Figma, Pytest

Paradigms

Mobile Development, Object-oriented Programming (OOP), Automation, User Acceptance Testing (UAT), ETL, Search Engine Optimization (SEO)

Platforms

Amazon Web Services (AWS), WordPress, iOS, Android, Docker, Kubernetes, Databricks

Other

Debugging, Web Development, Interviewing, Code Review, Technical Hiring, Source Code Review, Task Analysis, Mobile Applications, Mobile Apps, Single-page Applications (SPA), Strapi, Data Transformation, Scripting, APIs, Responsive Web Apps, Full-stack, Back-end, Minimum Viable Product (MVP), Front-end, Scraping, App Store, FastAPI, Zustand, Software Project Management, WebSockets, Apollo, Monorepos, Prefect, Data Warehouse Design, ELT, ETL Testing, Singer ETL, Google Play Console

Storage

PostgreSQL, Data Pipelines, Databases, MySQL, MongoDB, NoSQL, Redshift

2010 - 2015

Bachelor's Degree in Mechanical Engineering

Istanbul Technical University - Istanbul, Turkey

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