Alexandros is available for hire

Alexandros Elegreris

Verified Expert in Engineering

Full-stack Developer

Athens, Central Athens, Greece

Toptal member since March 4, 2024

Expertise

Web Development Full-stack Back-end Developers AWS RDS API Web Scraping Data Engineering Multithreading Data Scraping Integration

Bio

Alexander is an engineer who excels in various environments, from the fast-paced tech hubs of New York to the demanding ecosystems of Zurich. He has led transformative projects that have significantly improved system performance and operational efficiency. With experience leading teams in the Agile methodology, Alexandros' approach combines technical mastery with visionary leadership, driving his teams toward groundbreaking achievements.

Portfolio

Westmark Retail Ltd

Python, Django, FastAPI, SaaS, Queue Management, RabbitMQ, ZeroMQ...

Web3 Labs FZE

Trading Bots, Smart Contracts, Blockchain, Python, Solana, Cryptocurrency, Rust...

Scale Medicine Inc.

Python, Rust, MongoDB, Google Bucket, JSON, Amazon RDS, ChatGPT API, OpenAI API...

Experience

Python - 15 years
Relational Databases - 10 years
Microservices - 7 years
API Architecture - 7 years
Amazon Web Services (AWS) - 7 years
NoSQL - 7 years
FastAPI - 3 years
WebSockets - 3 years

Availability

Part-time

Preferred Environment

Linux, Windows, Slack

The most amazing...

...thing I've worked on is a system for managing manual and automatic trades, enhancing the reliability of trading operations for the largest crypto ETF.

Work Experience

Back-end Python Engineer

2024 - PRESENT

Westmark Retail Ltd

Led the architecture and development of a scalable SaaS platform using Python and FastAPI. While building the system, I mentored junior engineers, guiding them through best practices in API design, cloud deployment, and database optimization.
Provided hands-on mentorship in front-end development with Next.js, ensuring seamless integration. I emphasized clean code, maintainability, and performance, shaping a team that could independently design and scale complex systems.
Taught the team how to implement efficient asynchronous task execution. By introducing scalable patterns on AWS and Google Clod Platform (GCP), I helped them understand cloud infrastructure, improving deployment strategies and system reliability.

Technologies: Python, Django, FastAPI, SaaS, Queue Management, RabbitMQ, ZeroMQ, Amazon Web Services (AWS), Google Cloud Platform (GCP), Minimum Viable Product (MVP), Supabase, Amazon RDS, Event-driven Architecture, Server-side, Firebase, Google Cloud Functions

Senior Trading Engineer

2024 - 2025

Web3 Labs FZE

Built a high-frequency trading bot using Rust, optimizing for true concurrency and ultra-low latency. Kafka, nng, and Flink handled real-time data streaming, ensuring rapid market analysis and execution.
Leveraged PostgreSQL and Redis to store data for later analysis, optimizing speed and reliability. The algorithms were fine-tuned for precision.
Used Next.js to power the front end, providing real-time insights and controls. By integrating advanced concurrency models, the bot executed trades with minimal delay, maximizing efficiency in algorithmic trading.

Technologies: Trading Bots, Smart Contracts, Blockchain, Python, Solana, Cryptocurrency, Rust, Minimum Viable Product (MVP), Cryptocurrency Trading, Cryptocurrency Exchanges, Binance API, Binance Cryptocurrency Exchange, Coinbase API, Ethereum, Amazon RDS, Express.js, Responsiveness, ChatGPT API, OpenAI API, Server-side, Natural Language Processing (NLP), Data Processing, Google Cloud Functions, TradingView, Large Language Models (LLMs), AI Chatbots, Chrome Extensions, Prompt Engineering

Senior Data Engineer

2024 - 2024

Scale Medicine Inc.

Scraped terabytes of data using Python and Rust, automating large-scale collection from diverse sources. Python handled the data retrieval and processing, while Rust ensured true concurrency, maximizing speed and efficiency.
Used Rust-powered parsers that cleaned, normalized, and structured raw data in parallel, handling formats like JSON, CSV, and XML. This approach allowed efficient, high-performance transformation of unstructured data into a reliable format.
Structured the processed data for machine learning training, using PostgreSQL and MongoDB for optimized storage. This enabled seamless AI model integration, improving predictions and driving actionable insights.

Technologies: Python, Rust, MongoDB, Google Bucket, JSON, Amazon RDS, ChatGPT API, OpenAI API, Server-side, Natural Language Processing (NLP), Data Processing, Google Cloud Functions, Playwright, Chrome Extensions, Large-scale Web Crawlers

Senior Web Engineer

2024 - 2024

Caravan Tours Inc.

Built high-efficiency ETL pipelines (Python/Go/Spark) handling structured/unstructured data at scale. Slashed latency via workflow optimizations, enabling real-time insights.
Architected systems using FastAPI, Go concurrency, and Kafka to handle 10,000+ events per second. Used Redis and RabbitMQ to eliminate bottlenecks, reducing DB load by 60%. Built for resilience, ensuring smooth performance even under spike loads.
Transformed data into growth drivers and migrated to DynamoDB, reducing query costs by 55%. Leveraged OpenAI to auto-tag customer feedback, seamlessly integrating it into roadmaps.
Built compliant pipelines that passed rigorous fintech audits. Data that solves, never complicates.

Technologies: Web Scraping, JSON, Website Data Scraping, Python, MongoDB, ETL, Claude, OpenAI, Minimum Viable Product (MVP), Coinbase API, Amazon RDS, ChatGPT API, OpenAI API, Large Language Models (LLMs), Server-side, Natural Language Processing (NLP), Data Processing, AI Chatbots, Playwright, Chrome Extensions, Prompt Engineering

Principal Engineer

2022 - 2024

Stork

Led a team of five engineers in the evaluation and re-architecture of the entire infrastructure, significantly increasing system speed and efficiency while reducing operational costs.
Worked on the monolithic design on AWS, using Rust for efficient high-speed signing; Python, FastAPI, and Redis for rapid result processing; and Docker for containerization, establishing Stork as a premier ultra-low latency reference price provider.
Created a tailored weighted mark price oracle for Vertex.
Led the engineering team focusing on Agile methodology practices. Successfully implemented strategies that improved project agility and team dynamics.
Piloted large-scale projects, including Web3 and blockchain initiatives, propelling company growth and market success.
Created a tailored spot oracle for OKX and an integration infrastructure for their custom API.

Technologies: Amazon Web Services (AWS), API Architecture, Amazon DynamoDB, FastAPI, Redis, Rust, Low Latency, RabbitMQ, Algorithms, High-load, Relational Databases, Python, Docker, Kubernetes, GitHub, CI/CD Pipelines, WebSockets, Code Review, Back-end, APIs, Asynchronous Programming, Unit Testing, Code Refactoring, Database Modeling, SQL, Apache Kafka, Back-end Development, Containerization, Database Design, Database Optimization, Leadership, Performance Optimization, RESTful Services, Scalability, Technical Leadership, DevOps, Architecture, MongoDB, API Integration, Finance, Finance APIs, Trading Systems, Agile, REST APIs, Back-end Architecture, Management, Delivery Management, Engineering Management, Software Architecture, Web Development, Web Applications, Web Dashboards, JSON, Pytest, Abstract Syntax Trees (AST), Databricks, AI Integration, Data Science, Data Architecture, Cloud Native, Cloud Deployment, AWS Lambda, Message Queues, Serverless, API Design, API/Services Architecture, Integration, API Gateways, Microservices Architecture, Auth0, SQLAlchemy, Data Pipelines, Blockchain, Cryptocurrency, Python Asyncio, Socket.IO, Scalable Web Services, Databases, Bloomberg API, Matplotlib, Pandas, Financial Data, Statistics, Project Planning, Requirements Analysis, Project Timelines, Amazon S3 (AWS S3), OpenAI, ChatGPT, REST, Data Analytics, Cloud Infrastructure, Startups, C#, Bloomberg, Financial Markets, Data Engineering, API Databases, Interactive Brokers API, Real-time Data, Trading Bots, Python API, Stock Market, Stock Trading, Tickers, Profit & Loss (P&L), Stock Exchange, Trade Finance, API Development, Git, Fintech, Payment APIs, ZeroMQ, Queue Management, Redis Cache, Smart Contracts, ECS, Futures & Options, Multithreading, Python 3, Asyncio, Multiprocessing, Cryptocurrency Trading, Minimum Viable Product (MVP), Cryptocurrency Exchanges, Binance API, Binance Cryptocurrency Exchange, Coinbase API, Ethereum, Amazon RDS, Event-driven Architecture, AWS CloudFormation, Responsiveness, Server-side, Amazon CloudWatch, Terraform, Proof of Concept (POC), Firebase, Data Processing

Senior Software and Trading Engineer

2022 - 2023

21.co

Co-led a team of over eight engineers, co-designed and co-built a full-stack, microservices-based order management system (OMS) using Python, FastAPI, RabbitMQ, and Redis, containerized with Docker, orchestrated with Kubernetes, and deployed on AWS.
Worked on a system vital for managing manual and automatic trades, enhancing the scalability and reliability of trading operations for the world's largest crypto ETF.
Developed a high-frequency trading (HFT) low latency system with a monolithic design using Rust and C++, significantly enhancing the trading capabilities and performance of the world's largest crypto exchange-traded funds (ETF).
Led the design and implementation of an identity access management (IAM) system for the OMS, ensuring secure and efficient trader operations in a blockchain-centric environment.
Partnered with world-class traders from Bank of America, Deutsche Bank, and UniCredit to translate complex trading strategies into effective, reliable algorithms.
Managed comprehensive testing and maintenance protocols for trading systems, focusing on speed optimization, bug resolution, and edge case identification to guarantee robustness in live trading environments.

Technologies: Amazon Web Services (AWS), API Architecture, Microservices, Docker, Kubernetes, Amazon EKS, Python, FastAPI, RabbitMQ, Redis, Go, Rust, Low Latency, Trading, Algorithms, NoSQL, C++, Next.js, TypeScript, GitHub, CI/CD Pipelines, Code Review, Algorithmic Trading, Interviewing, WebSockets, High-load, Back-end, APIs, Asynchronous Programming, Unit Testing, Code Refactoring, JavaScript, Database Modeling, UI Design, SQL, Apache Kafka, Back-end Development, Containerization, Database Design, Database Optimization, Leadership, Performance Optimization, RESTful Services, Scalability, Technical Leadership, DevOps, Full-stack, Software Design, Architecture, MongoDB, API Integration, Finance, Finance APIs, Trading Systems, React, Agile, Full-stack Development, REST APIs, Back-end Architecture, Websites, CSS, HTML, Node.js, Management, Delivery Management, Engineering Management, Software Architecture, Automation, UI Automation, Workflow Automation & System Integration, Selenium, Web Development, Puppeteer, Generative Pre-trained Transformers (GPT), Web Applications, OpenAI GPT-4 API, Web Dashboards, Web Scraping, Data Scraping, Website Data Scraping, JSON, Pytest, Abstract Syntax Trees (AST), Databricks, Data Science, User Experience (UX), User Interface (UI), Data Architecture, Front-end Development, Cloud Native, Artificial Intelligence (AI), Cloud Deployment, AWS Lambda, Message Queues, Serverless, Amazon Simple Queue Service (SQS), API Design, API/Services Architecture, Integration, API Gateways, Microservices Architecture, Angular, Okta, SQLAlchemy, Graphical User Interface (GUI), Data Pipelines, Blockchain, Cryptocurrency, Python Asyncio, Socket.IO, Databases, Bloomberg API, Matplotlib, Pandas, Financial Data, Statistics, Project Planning, Requirements Analysis, Project Timelines, Amazon S3 (AWS S3), AI Website Builders, Web Crawlers, OpenAI, ChatGPT, REST, Data Analytics, Cloud Infrastructure, NestJS, Bloomberg, Financial Markets, Data Engineering, API Databases, HTML5, PDF Scraping, Interactive Brokers API, Real-time Data, Time Series, Time Series Analysis, Trading Bots, Python API, Stock Market, Stock Trading, Tickers, Hedge Funds, Options Trading, Profit & Loss (P&L), Stock Exchange, Trade Finance, API Development, Git, Fraud Prevention, Fraud Detection, Fintech, Payment APIs, ZeroMQ, Queue Management, Redis Cache, Smart Contracts, Solana, DOM, ECS, Futures & Options, Multithreading, Python 3, Asyncio, Multiprocessing, Cryptocurrency Trading, Minimum Viable Product (MVP), Supabase, Cryptocurrency Exchanges, Binance API, Binance Cryptocurrency Exchange, Ethereum, Amazon RDS, Event-driven Architecture, AWS CloudFormation, Responsiveness, Server-side, Amazon CloudWatch, Terraform, Proof of Concept (POC), Data Processing, TradingView

Senior Software Engineer

2022 - 2022

Embed

Redesigned the architecture and infrastructure, helping the team deal with the increased volume of traffic that their previous architecture could not handle.
Worked on the redesign that saved operating costs and the new architecture that simplified the complicated schema and helped speed up maintenance and new feature development.
Assisted the business in shaping many of their ideas into effective products.
Consulted on various security matters and erased previous technical debt.

Technologies: API Architecture, Python, FastAPI, Flask, GraphQL, Node.js, TypeScript, Microservices, Back-end, APIs, Code Refactoring, Database Modeling, UI Design, SQL, Back-end Development, Containerization, Database Design, Database Optimization, Performance Optimization, RESTful Services, Scalability, Full-stack, Architecture, MongoDB, Agile, REST APIs, Back-end Architecture, Google Cloud, Software Architecture, Web Development, Web Applications, JSON, Data Architecture, Vue, Front-end Development, Cloud Native, Cloud Deployment, Tailwind CSS, Message Queues, API Design, API/Services Architecture, Email Automation, Microservices Architecture, Auth0, SQLAlchemy, Data Pipelines, Blockchain, Cryptocurrency, Python Asyncio, Socket.IO, Databases, Pandas, Project Planning, Requirements Analysis, Project Timelines, REST, Cloud Infrastructure, Startups, API Databases, HTML5, Google Cloud Platform (GCP), Python API, API Development, X (formerly Twitter) API, Git, Express.js, SaaS, DOM, Python 3, Asyncio, Multiprocessing, Minimum Viable Product (MVP), Social Media APIs, Search Engine Optimization (SEO), Responsiveness, Server-side, Airtable, Proof of Concept (POC), Google Cloud Functions, Chrome Extensions, eCommerce

Principal Engineer

2018 - 2022

ClearViewAI

Developed pipelines, databases, and APIs, primarily built in Python, certifying that they were robust, efficient, and fast enough to handle data on the scale of hundreds of terabytes. Used Redis, MongoDB, RabbitMQ, PostgreSQL, and Spark.
Developed advanced web crawlers by leveraging Python, JavaScript, and Node.js in combination with Selenium, BeautifulSoup, and a custom Chromium-based browser. Custom anti-evasion techniques and traffic analysis further refined the process.
Developed software verification plans and quality assurance procedures and troubleshot, debugged, and upgraded existing systems.
Led a team of more than 12 engineers focusing on Agile methodology practices and successfully implemented strategies that improved project agility and team dynamics.

Technologies: Amazon Web Services (AWS), ETL, NoSQL, Redis, PostgreSQL, Python, Selenium, Java, API Architecture, C++, Flask, JavaScript, Docker, Kubernetes, GitLab, Machine Learning, Code Review, Interviewing, React, Bots, Scraping, Back-end, APIs, Asynchronous Programming, Unit Testing, Code Refactoring, Database Modeling, UI Design, SQL, RabbitMQ, Back-end Development, Containerization, Database Design, Database Optimization, Leadership, Performance Optimization, RESTful Services, Scalability, Technical Leadership, DevOps, Full-stack, Software Design, Architecture, MongoDB, Agile, Full-stack Development, REST APIs, WebRTC, Back-end Architecture, Websites, CSS, HTML, React Native, Management, Delivery Management, Engineering Management, Software Architecture, Automation, UI Automation, Workflow Automation & System Integration, Web Development, Algorithms, Beautiful Soup, Puppeteer, Web Applications, Web Dashboards, Web Scraping, Data Scraping, F5 Networks, Website Data Scraping, JSON, Pytest, AI Integration, Data Science, User Experience (UX), User Interface (UI), Data Architecture, Front-end Development, Cloud Native, Artificial Intelligence (AI), Cloud Deployment, Message Queues, API Design, API/Services Architecture, Microservices Architecture, MySQL, SQLAlchemy, Graphical User Interface (GUI), Data Pipelines, Python Asyncio, Celery, Scalable Web Services, Databases, Pandas, Project Planning, Requirements Analysis, Project Timelines, Amazon S3 (AWS S3), Web Crawlers, Scrapy, REST, Data Analytics, Cloud Infrastructure, Startups, C#, Data Engineering, API Databases, HTML5, PDF Scraping, Real-time Data, Google Cloud Platform (GCP), Apache Airflow, Python API, API Development, X (formerly Twitter) API, Git, Mobile Development, ZeroMQ, Queue Management, Redis Cache, DOM, ECS, Multithreading, Python 3, Asyncio, Multiprocessing, Minimum Viable Product (MVP), Social Media APIs, Search Engine Optimization (SEO), Responsiveness, Server-side, Terraform, Proof of Concept (POC), Maps, Data Processing, Google Cloud Functions, Playwright, Chrome Extensions, Large-scale Web Crawlers

Senior Software Engineer

2014 - 2017

Artiusio

Developed and worked on enterprise software for medium and large-size corporations.
Configured and deployed enterprise software for various hotels and businesses. Created a customer relationship management (CRM) and a booking solution consisting of a desktop and a web application.
Monitored and updated client websites while playing a key role in expanding the company's and client's operations.

Technologies: Django, Python, Amazon Web Services (AWS), Web Development, PostgreSQL, WordPress, Back-end, APIs, Code Refactoring, UI Design, SQL, Back-end Development, Containerization, RESTful Services, Full-stack, Software Design, Full-stack Development, REST APIs, Back-end Architecture, Websites, CSS, HTML, Software Architecture, Web Applications, JSON, User Experience (UX), User Interface (UI), Front-end Development, Cloud Native, Message Queues, API Design, API/Services Architecture, MySQL, Booking, SQLAlchemy, Graphical User Interface (GUI), Content Management Systems (CMS), Databases, Pandas, R, Requirements Analysis, Project Timelines, Mailchimp, REST, C#, API Databases, HTML5, Google Cloud Platform (GCP), Python API, API Development, Git, Mobile Development, SaaS, DOM, Python 3, Minimum Viable Product (MVP), Social Media APIs, Search Engine Optimization (SEO), Responsiveness, Server-side, Proof of Concept (POC), eCommerce

Experience

Facial Recognition

http://clearview.ai

I joined as one of the inaugural engineers at a budding startup before it even formalized its corporate entity. I dedicated countless hours to its development, and my commitment paid off as we ascended to become a leader in our industry, earning accolades, including mentions in The New York Times and being listed among the TIME100 Most Influential Companies of 2021.

Trading System

I was initially hired to develop an order management system (OMS) for manual trading. I spearheaded the project's expansion to create a comprehensive OMS that supports algorithmic and high-frequency trading and delivers real-time data. This endeavor was enriched through collaboration with world-class quants from leading financial institutions, including Bank of America, Deutsche Bank, and UniCredit, significantly enhancing the system's functionality and impact.

Stork

I optimized an overly complex and costly price oracle provider by reducing operational costs by more than half and streamlining its design with essential tools. This significantly boosted its speed, enabling the project to withstand the challenges of the crypto winter.

Skills

Libraries/APIs

React, Node.js, REST APIs, Beautiful Soup, Puppeteer, SQLAlchemy, Python Asyncio, Socket.IO, Python API, API Development, Asyncio, Binance API, Coinbase API, Playwright, ZeroMQ, Vue, Bloomberg API, Matplotlib, Pandas, Interactive Brokers API, X (formerly Twitter) API, Social Media APIs, OpenAI API, WebRTC

Tools

Pytest, ChatGPT, Git, RabbitMQ, Amazon EKS, GitHub, GitLab, Amazon Simple Queue Service (SQS), Auth0, Celery, Mailchimp, Bloomberg, AWS CloudFormation, Amazon CloudWatch, Terraform, Slack, Apache Airflow, Claude

Languages

Python, C++, TypeScript, JavaScript, CSS, HTML, SQL, C#, HTML5, Python 3, Go, Java, GraphQL, Rust, R

Frameworks

Django, Next.js, Selenium, Scrapy, Flask, gRPC, React Native, Tailwind CSS, NestJS, Express.js, Angular

Paradigms

ETL, Asynchronous Programming, Unit Testing, Database Design, Agile, Back-end Architecture, Management, Automation, API/Services Architecture, Microservices Architecture, Requirements Analysis, REST, Microservices, API Architecture, Code Refactoring, UI Design, DevOps, Mobile Development, Event-driven Architecture, Search Engine Optimization (SEO), Low-code Development

Platforms

Amazon Web Services (AWS), Cloud Native, AWS Lambda, Blockchain, Google Cloud Platform (GCP), Linux, Windows, Kubernetes, Docker, WordPress, Apache Kafka, Ethereum, Firebase, Databricks

Storage

PostgreSQL, Google Cloud, JSON, Cloud Deployment, MySQL, Data Pipelines, Databases, Amazon S3 (AWS S3), API Databases, MongoDB, Amazon DynamoDB, Redis, Relational Databases, NoSQL, Database Modeling, Redis Cache, Google Bucket

Industry Expertise

Binance Cryptocurrency Exchange, Trading Systems

Other

FastAPI, WebSockets, Web Development, Bots, Full-stack, Scraping, Back-end, APIs, Back-end Development, Containerization, Leadership, Performance Optimization, RESTful Services, Scalability, Technical Leadership, Architecture, API Integration, Full-stack Development, Delivery Management, Engineering Management, UI Automation, Workflow Automation & System Integration, Web Applications, Web Scraping, Data Scraping, F5 Networks, Website Data Scraping, Data Architecture, Message Queues, Serverless, API Design, Integration, API Gateways, Cryptocurrency, Scalable Web Services, Project Planning, Project Timelines, Web Crawlers, Startups, Financial Markets, Data Engineering, Real-time Data, Trading Bots, DOM, Multithreading, Multiprocessing, Cryptocurrency Trading, Minimum Viable Product (MVP), Cryptocurrency Exchanges, Amazon RDS, Server-side, Proof of Concept (POC), Data Processing, Google Cloud Functions, Large-scale Web Crawlers, Low Latency, Trading, Algorithms, High-load, CI/CD Pipelines, Code Review, Algorithmic Trading, Interviewing, Database Optimization, Software Design, Finance, Finance APIs, Websites, Software Architecture, Generative Pre-trained Transformers (GPT), OpenAI GPT-4 API, Web Dashboards, Abstract Syntax Trees (AST), AI Integration, Data Science, User Interface (UI), Front-end Development, Artificial Intelligence (AI), Okta, Booking, Graphical User Interface (GUI), Content Management Systems (CMS), Financial Data, OpenAI, Data Analytics, Cloud Infrastructure, PDF Scraping, Time Series, Time Series Analysis, Stock Market, Stock Trading, Tickers, Hedge Funds, Options Trading, Profit & Loss (P&L), Stock Exchange, Trade Finance, Fintech, Payment APIs, Queue Management, SaaS, Smart Contracts, Solana, ECS, Futures & Options, Supabase, Responsiveness, ChatGPT API, Large Language Models (LLMs), Natural Language Processing (NLP), Maps, TradingView, AI Chatbots, Chrome Extensions, eCommerce, Prompt Engineering, Machine Learning, Low-latency Software, User Experience (UX), Email Automation, Statistics, AI Website Builders, Fraud Prevention, Fraud Detection, Airtable

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