David Gero, Developer in Szeged, Hungary
David is available for hire
Hire David

David Gero

Verified Expert  in Engineering

Bio

David is an experienced, self-taught Ruby and Ruby on Rails developer who started his career in computational linguistics nearly a decade ago. Initially, he worked on different NLP projects but soon focused on web application development. David has worked across multiple industries, such as eCommerce, education, business technology, and procurement, and he has even created his own profitable app.

Portfolio

Toptal
Ruby, Ruby on Rails (RoR), Docker, GraphQL, Redis, PostgreSQL, Sidekiq
Tezisto
Ruby, Shopify, Ruby on Rails (RoR), React, Heroku, Shopify API, Shopify Theme...
Fuse Universal
Ruby, Ruby on Rails (RoR), Python, Pandas, Amazon EC2, Capistrano, MySQL, Auth0...

Experience

Ruby on Rails (RoR) - 10 yearsRuby - 10 yearsPython - 6 yearsPandas - 5 yearsLinux - 5 yearsShopify - 5 yearsGenerative Pre-trained Transformers (GPT) - 4 yearsComputational Linguistics - 4 years

Availability

Part-time

Preferred Environment

Linux, MacOS, Ruby, Python, Shopify

The most amazing...

...thing I've done was founding a startup following the customer development methodology. I've presented pitches and sold the app before building it.

Work Experience

Back-end Engineer

2022 - 2023
Toptal
  • Worked as a core developer in the improvement of Toptal's recruiting processes using Ruby on Rails.
  • Implemented new features and ran A/B tests to fine-tune the different business processes.
  • Added new tasks and maintained older ones to smooth the overall recruiting experience.
Technologies: Ruby, Ruby on Rails (RoR), Docker, GraphQL, Redis, PostgreSQL, Sidekiq

Founder and Developer

2020 - 2022
Tezisto
  • Launched the Product Passage App in the Shopify App Store to help companies increase sales through the major Hungarian product and price comparison site.
  • Led the business development process following the customer development methodology. Conducted interviews, wrote and presented pitches, managed operations from start to finish, hired specialists, and led incremental improvements.
  • Helped, as a Shopify expert, over 30 stores automate logistics and data synchronization processes to run their businesses as smoothly as possible.
Technologies: Ruby, Shopify, Ruby on Rails (RoR), React, Heroku, Shopify API, Shopify Theme, Shopify Payments, PostgreSQL, GraphQL

Ruby on Rails Developer

2020 - 2021
Fuse Universal
  • Created a custom learning platform with Ruby on Rails for B2B clients, helping to share knowledge and expertise within their companies.
  • Handled custom integration with Auth0, a fully managed authentication and authorization service to increase security and portability with the clients' systems.
  • Added new features and maintained old ones while creating multiple microservices and running them on their own servers or as a serverless solution like AWS Lambda in Ruby and Node.js.
Technologies: Ruby, Ruby on Rails (RoR), Python, Pandas, Amazon EC2, Capistrano, MySQL, Auth0, RSpec, Docker

Ruby on Rails Developer

2019 - 2020
Purchasing Platform Inc
  • Created a custom B2B procurement and eCommerce platform with Ruby on Rails and Go for the manufacturing housing industry.
  • Provided data-driven suggestions that helped stakeholders make better decisions in defining resource requirements.
  • Built multiple microservices from the monolith Ruby on Rails application in Ruby and Go.
Technologies: Ruby, Ruby on Rails (RoR), Linux, Go, Bash, Amazon EC2, Ansible, Capistrano, PostgreSQL, RSpec, Capybara

Search Engineer

2017 - 2018
Cookpad
  • Testimonial: "There are 100 million people on average in more than 70 countries with over 30 languages using Cookpad every month."
  • Worked as a search engineer at Cookpad, a recipe-sharing platform.
  • Created and maintained the language pre- and post-processing in Ruby and Python, which was used for indexing millions of recipes in different languages on ElasticSearch.
  • Implemented language model editors on Ruby on Rails to fine-tune language models and improve the search experience.
Technologies: Ruby, Ruby on Rails (RoR), Python, Elastic, Natural Language Processing (NLP), Generative Pre-trained Transformers (GPT), Docker, Amazon EC2, Bash, Pandas, PostgreSQL, Redis, Sidekiq

Software Developer

2016 - 2017
Analogy
  • Created a semantic search engine and automated semantic graphs in English and Hungarian language for tax advisors to speed up the searching, finding, extracting, and comparing millions of tax documents.
  • Built the web application in Ruby on Rails and the NLP data pipeline in Python and connected the different parts of the system with RabbitMQ (message bus).
  • Handled machine learning with SciPy and Scikit, data analysis with NumPy and Pandas, and NLP with NLTK and spaCy.
Technologies: Ruby, Ruby on Rails (RoR), Python, Natural Language Toolkit (NLTK), SpaCy, Pandas, RabbitMQ, Generative Pre-trained Transformers (GPT), Natural Language Processing (NLP), Bash, Ansible, Docker, Amazon EC2, RSpec, Capybara, PostgreSQL, Redis, Neo4j

Ruby on Rails Developer

2013 - 2015
Red Steed Studios Kft
  • Created a web application and API using Ruby on Rails for Bitcoin and Stellar cryptocurrency ATM and mobile application.
  • Progressed from being the first developer to being part of a growing team of 10 people, including mobile app developers, testers, and back-end developers.
  • Reported directly to the stakeholders as part of my role.
  • Kept the design flexible due to the multiple changes in the base cryptocurrency.
Technologies: Ruby, Ruby on Rails (RoR), Heroku, Google Protocol Buffer, Stellar SDK, Bitcoin, Fintech, PostgreSQL, RSpec, Capybara

Product Passage

https://tezisto.com/product-passage/
As a founder of the app, I conducted market research, pitched, copywrote, sold, built, developed, maintained, and supported the whole application. At the same time, I hired external experts to update different parts of the system.
2008 - 2014

Bachelor's Degree in Hungarian Expert and Language Technolog

University of Szeged - Szeged, Hungary

MARCH 2023 - PRESENT

Mastering Value Propositions

Strategyzer

OCTOBER 2020 - OCTOBER 2021

App Development Certification

Shopify Partner Academy

MAY 2016 - APRIL 2017

Inbound Sales Certification

HubSpot Academy

Libraries/APIs

Pandas, Natural Language Toolkit (NLTK), SpaCy, Sidekiq, React, Shopify API

Tools

Elastic, RabbitMQ, Stellar SDK, Ansible, Capistrano, RSpec, Auth0

Languages

Ruby, Python, Go, Bash, GraphQL

Frameworks

Ruby on Rails (RoR), Google Protocol Buffer, Capybara

Platforms

Shopify, Linux, Heroku, Docker, Amazon EC2

Storage

PostgreSQL, MySQL, Redis, Neo4j

Other

Computational Linguistics, Natural Language Processing (NLP), Web Marketing, Sales, Tech Sales, Bitcoin, Fintech, Shopify Theme, Shopify Payments, Value Proposition, Value Proposition Design, Generative Pre-trained Transformers (GPT)

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.

1

Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring