Csongor Józsa
Verified Expert in Engineering
Full-stack Developer
Budapest, Hungary
Toptal member since December 23, 2020
Csongor has been a software developer since 2009, specializing in JavaScript (React, Node.js, Gatsby) and Python (Django, Flask) based systems. As a polyglot programmer, he writes robust, high-quality, and well-tested code and is a test-driven development (TDD)/clean code enthusiast. In addition to experience with DevOps tooling and system administration, Csongor has a particular interest in web application security.
Portfolio
Experience
- JavaScript - 14 years
- Python - 10 years
- Test-driven Development (TDD) - 4 years
- PostgreSQL - 4 years
- Node.js - 4 years
- React - 4 years
- TypeScript - 3 years
- Redux - 2 years
Availability
Preferred Environment
Amazon Web Services (AWS), Docker, Heroku, Linux
The most amazing...
...project I've been part of was designing and building a complex data pipeline for professional sports analysis and data visualization used by several NBA teams.
Work Experience
Principal Software Engineer
Ido Portal Ltd.
- Rearchitected the main media conversion pipeline using AWS cloud solutions. Successfully planned and executed the migration of media data to the new system.
- Planned and implemented a solution for secure video distribution.
- Collaborated with the stakeholders to identify pain points and bottlenecks and implemented various fixes and improvements that streamlined user's workflow.
Senior Software Engineer
Allegis - Cruise Automation - Main
- Acted as a release manager, reviewing PRs and ensuring the release process went smoothly.
- Assisted the QA team in planning the expansion of their testing strategy to include component and integration testing. Also helped identifying areas where the team could move towards automated testing instead of repetitive manual processes.
- Acted as a technical mentor for an intern, helping him get familiar with the stack and the codebase, giving feedback on PRs, etc.
- Planned and implemented the migration of the React codebase from Flow to TypeScript, enabling the engineering team to catch and fix defects earlier in the development process. This significantly reduced the number of bugs making it to production.
- Assisted in identifying, prioritizing, and fixing a number of performance bottlenecks in the React-based front-end application. Managed to reduce the number of crashes and achieved huge rendering speed improvements.
- Refactored sections of the main React app to use Redux middleware instead of Redux-Saga to streamline the codebase.
- Improved the quality of the React codebase by refactoring the usage of algebraic data types from Fantasyland.
- Refactored parts of the React application using RxJS, resulting in code that is more streamlined and easier to maintain.
Lead Engineer
Much Better Adventures
- Migrated parts of the monolithic Django application to a modern front-end app using React and Next.js.
- Designed and built microservices for new feature sets, such as a new payment gateway, using React (TypeScript, Redux, Material UI), Flask, Django (DRF), and PostgreSQL, contributing to the effort to move away from the monolithic architecture.
- Acted as the lead engineer, collaborating closely with the CTO regarding technical decisions related to system architecture.
- Maintained and continuously improved the code quality of the main legacy application, which was built with Django and a Django REST framework API.
- Collaborated with the customer support team to enhance workflow efficiency. Created various tools, including some intercom apps using Python, Flask, stream.io, and serverless.
- Helped the client to move away from a monolithic design towards a microservice-based architecture. Designed and implemented the JWT-based authentication scheme between the different microservices.
- Migrated the main application's CI pipeline from GitLab to GitHub.
Application Security Engineer
Emarsys
- Developed and maintained several sensitive and/or security-related product features and libraries, such as authentication, authorization, session handling, encryption, and data sanitization using JavaScript, TypeScript, Python, Go, PHP, and Ruby.
- Created risk assessment and threat modeling tools using Django and Flask.
- Designed and built a secure-by-default, easy-to-use cryptographic library for Python (github.com/emartech/python-easy-crypto) for securing data transfer between microservices.
- Set up, developed, and maintained automated tools to help development teams ship secure product features using Python, ElasticSearch, Logstash, Kibana, MySQL, and Zed Attack Proxy.
- Developed and maintained a set of AWS-compatible request signing libraries (Escher: escherauth.io/index.html), implemented in various languages, including Node.js, Python, Go, and PHP.
- Played a crucial role in finding and fixing web application vulnerabilities. Also participated in planning and implementing security incident response strategies.
- Enabled development teams to apply security best practices daily by providing one-on-one mentoring and consultation, developing training materials, and setting up secure development guidelines.
- Played a key role in preparing for external audits and penetration tests, evaluating the results, and following up on possible findings.
- Assisted development teams in secure data handling and GDPR-related design decisions.
- Built an in-house CI monitoring/alerting using Silex, MongoDB, and Angular and integrating with Heroku and GitHub APIs.
Software Developer
Webpont
- Developed data visualization tools for sports analytics software and implemented computer vision algorithms to analyze professional sports videos.
- Bootstrapped the back-end engine for a forex copy trading platform.
- Designed, built, and maintained an automated email marketing platform with advanced segmentation and personalization capabilities. The platform is optimized for sending high-volume emails.
- Developed a custom CMS for an international grocery store chain.
Experience
Scenario Editor for Testing Autonomous Vehicles
https://getcruise.comMuch Better Adventures
https://www.muchbetteradventures.com/As the lead engineer for the company, I played a key role in driving technical decisions, moving the system from a monolithic application toward a more modern microservice-based architecture, and ensuring high code quality standards.
Application Security Pipeline for Emarsys
https://emarsys.com/Tesco Central Europe
Authentication Solutions for Emarsys Marketing Platform
https://emarsys.com/Cryptographic Library for Python
https://github.com/emartech/python-easy-cryptoReal Estate Portal
Web3 Front End for Decentralized Finance Functionality of a Community-driven Crypto Token
https://github.com/jcsongor/scam-dappMedia Conversion Pipeline for Online Movement Education Platform
Education
Bachelor's Degree in Computer Science and Engineering
Budapest University of Technology and Economics - Budapest, Hungary
Coursework Toward a Master’s Degree in Physics
Eötvös Loránd University (ELTE) - Budapest, Hungary
Skills
Libraries/APIs
React, REST APIs, Django ORM, Node.js, Stripe, SQLAlchemy, OpenCV, jQuery, Auth, Intercom API, Zendesk API, API Development, React Redux, Stripe API, WebGL, Three.js, OpenGL, Ramda, RxJS, Redux-Saga, Web3.js, Mapbox API, Rollbar
Tools
Elastic, Kibana, ELK (Elastic Stack), OWASP Zed Attack Proxy (ZAP), OpenVPN, Docker Swarm, Logstash, Apache, SendGrid, Git, Jira, Google Analytics, Sentry, Pytest, Knex.js, Flow, MetaMask, AWS IAM, Papertrail, GitHub
Languages
Python, JavaScript, PHP, SQL, HTML, CSS, TypeScript, Ruby, C, C++, Bash Script, CoffeeScript, Bash, Java, Go, GraphQL, HTML5, Python 3, Python 2, Solidity, Elixir
Frameworks
Django, Flask, Redux, Django REST Framework, JSON Web Tokens (JWT), Ruby on Rails (RoR), Yii, Silex, CakePHP, AngularJS, Angular, Express.js, Koa, Phoenix, Video.js, Cypress, Jest, Tailwind CSS, Next.js
Paradigms
Test-driven Development (TDD), REST, DevSecOps, DevOps, Automated Testing, Web Architecture, API Architecture, REST API Architecture, API/Services Architecture, Continuous Deployment, Continuous Delivery (CD), Continuous Integration (CI), Functional Programming, Microservices, Microservices Architecture
Platforms
Linux, Heroku, Docker, Amazon Web Services (AWS), WordPress, LAMP, Google Cloud Platform (GCP), Azure, Oracle, Zendesk, Contentful, Mapbox, Buildkite, Blockchain, AWS Lambda, Netlify
Storage
NoSQL, PostgreSQL, MySQL, Azure Active Directory, Elasticsearch, MongoDB, Memcached, Redis, Databases, Relational Databases, Amazon S3 (AWS S3)
Other
Web App Security, Back-end, APIs, Web Development, Front-end Development, Back-end Development, React Hooks, Full-stack, Gatsby, Serverless, Intercom, Single Sign-on (SSO), Security, IT Security, OWASP, Defect Management, Cryptography, General Data Protection Regulation (GDPR), Forex, Algorithms, Data Structures, Mathematics, Physics, Linear Algebra, Calculus, Defect Logging, Vulnerability Assessment, Vulnerability Management, Vulnerability Identification, Applied Cryptography, Advanced Encryption Standard (AES), Front-end, API Design, Storybook, HTTP, Ajax, Caching, Code Review, Payment APIs, Payment Gateways, Architecture, Code Architecture, API Applications, Stripe Payments, PostgreSQL 9, Maps, Web3, Smart Contracts, Cryptocurrency, Decentralized Finance (DeFi), Cryptocurrency Wallets, RESTful Microservices, Mapbox SDK, Software Development, Software Engineering, Amazon Elastic Transcoder, AWS Elemental MediaConvert, Turbolinks, Amazon EventBridge, CI/CD Pipelines, Video Streaming, Application Security, Secure Web Development, OWASP Top 10, Web Security, Public-key Cryptography, System Design, Full-stack Development
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