Peter Ujvari
Verified Expert in Engineering
Python Back-end Developer
Budapest, Hungary
Toptal member since December 7, 2021
Peter is a software architect with 18+ years of experience. He excels at solving problems and high-stakes architectural challenges, having managed systems with 450+ million records and 3.6+ million daily requests. Using Python and AWS, he builds resilient platforms optimized for cost and scale. A hands-on leader, Peter bridges the gap between product vision and complex technical reality.
Portfolio
Experience
- Software Development - 20 years
- Databases - 16 years
- Python - 10 years
- Node.js - 9 years
- Amazon Web Services (AWS) - 7 years
- Microservices - 6 years
- Software Architecture - 5 years
- Technical Leadership - 4 years
Preferred Environment
OS X, Slack, Skype, Google Meet, Visual Studio Code (VS Code), Terminal
The most amazing...
...achievement was turning a friction-filled roadmap into a collaborative success by bridging the gap between product vision and technical feasibility.
Work Experience
Engineering Manager
Lensa
- Led system design and architectural decisions for high-traffic distributed systems.
- Acted as technical advisor to product management — translated requirements into architectural plans and provided early feasibility assessments that mitigated delivery risk.
- Improved team workflows and delivery processes, increasing throughput and predictability.
- Grew and shaped the team — defined the technical hiring bar, interviewed candidates, and onboarded new engineers.
- Reduced infrastructure costs through technology selection and resource optimization. Drove modernization and refactoring of legacy components, reducing technical debt and improving maintainability.
- Strengthened collaboration and soft skills, including communication, prioritization, and facilitation, through targeted workshops.
- Assumed ownership of critical system components, ensuring stability and long-term maintainability.
- Built and rolled out an internal AI-augmented development platform spanning solution design, automated code review, TDD, and ticket-to-implementation workflows — adopted across the team to increase velocity and consistency.
- Introduced a code knowledge graph (RAG-over-code) with enforced discovery guardrails, replacing ad-hoc file search with structural queries and change-impact analysis.
- Codified architecture, code-quality, and testing standards as reusable AI review workflows, and built an internal knowledge base that accelerated onboarding and knowledge sharing.
Senior Software Engineer
Lensa
- Architected and delivered complete web applications and dozens of microservices end-to-end, from design and implementation to monitoring and scaling (system grew to around 17,000 new user registrations per day).
- Designed service-to-service communication (async, sync, Kafka, REST, etc) to ensure reliability and scalability.
- Operated high-traffic APIs serving 3.6+ million requests per day and asynchronous systems scheduling 90 million subscriptions, generating 17+ million daily personalized omni-channel messages.
- Architected and co-created an event processing service handling 35+ million daily events, powering engagement logic and BI data streams.
- Designed and optimized relational databases continuously, including rotating partitions and query optimization for 450+ million record datasets.
- Evaluated trade-offs regularly between architectural complexity, infra cost, dev effort, and business value, ensuring alignment with company goals.
- Implemented secure authentication solutions, including asymmetric methods.
- Introduced a monitoring solution adopted as a primary system-wide tool.
- Contributed to GitLab CI/CD pipeline setup, improving deployment reliability.
- Drove knowledge sharing through workshops (Python, Node.js, clean coding), mentoring, and interviewing engineering candidates.
Back-end Developer
Replise
- Developed the back end of an application that analyzed social media content and created many visualizations of useful and interesting information.
- Designed the architecture for the website and the entire automated crawling system.
- Implemented web crawlers for scraping web content from social media, news, and blog sites.
- Designed and maintained a NoSQL database for the system with MongoDB and Elasticsearch to store more than 80 million records for querying effectively.
Full-stack Developer
Extreme Digital
- Took part in the feature development and maintenance of one of the largest eCommerce systems in Hungary.
- Developed a new commenting and rating system for the products, including the front and back ends. This feature was used every day by hundreds of customers.
- Detected and fixed many bugs in the website and administration platform.
Full-stack Developer
KuponNet
- Created around 20 websites using the osCommerce framework.
- Developed many custom modules for the framework based on customers' needs.
- Implemented the HTML and CSS version of the design created in Photoshop.
Full-stack Developer
Trendency
- Built company and eCommerce websites using content management systems, such as Joomla.
- Implemented the HTML and CSS versions of Photoshop design files.
- Developed custom modules for these CMS systems based on the partners' needs.
Experience
High-traffic and Scalable Web Application and Services
http://lensa.comDeployment Service
Company and eCommerce Websites
Selenium-based Web Scraper
Skills
Libraries/APIs
Node.js, Asyncio, Beautiful Soup, REST APIs, React, OpenAPI, SQLAlchemy, Pandas, NumPy, Facebook API, Facebook SDK, Google API, Google APIs, PhantomJS, OpenCV
Tools
Celery, Amazon Simple Queue Service (SQS), AWS IAM, Claude, GitLab CI/CD, Slack, Skype, Google Meet, Terminal, Jira, Git, Adobe Photoshop, GitLab, Terraform
Languages
Python, JavaScript, HTML, SQL, PHP, CSS, Bash Script
Paradigms
Unit Testing, Microservices, Asynchronous Programming, REST, Object-oriented Programming (OOP), Object-oriented Design (OOD), API/Services Architecture, Functional Programming, Scrum, Kanban, Agile, DevOps, API Architecture, Serverless Architecture, Event-driven Programming, Event-driven Architecture, Scalable Application, Test-driven Development (TDD), Automated Testing, E2E Testing, Continuous Delivery (CD), Continuous Deployment, Design Patterns, Web Design Patterns
Platforms
AWS Lambda, Docker, Amazon Web Services (AWS), Twilio, Amazon EC2, Linux, OS X, Visual Studio Code (VS Code), WordPress, osCommerce, Joomla, WooCommerce, Windows, Google Chrome, Software Design Patterns, Firebase
Storage
Databases, MySQL, Redis, Amazon S3 (AWS S3), Amazon DynamoDB, NoSQL, Elasticsearch, Memcached, MongoDB, Microsoft SQL Server, SQL Stored Procedures, PostgreSQL, CouchDB
Frameworks
Flask, Scrapy, VirtueMart, Django, Symfony 2, Selenium, Chrome, Swagger, AWS Serverless Application Model (SAM)
Other
Back-end, Web Scraping, Architecture, Web Development, APIs, Scripting, Exports, API Integration, Serverless, Technical Leadership, Software Development, Solution Architecture, Third-party Integration, Workflows, Scalability, UML Diagrams, Containers, Enterprise Architecture, Analytics, AWS DevOps, Full-stack Development, Software Architecture, Domain-driven Design (DDD), FastAPI, Reports, Scraping, Data Scraping, CSV Export, Full-stack, Integration, CI/CD Pipelines, AI Integration, System Architecture, Large Language Models (LLMs), Technical Consulting, eCommerce, Performance Optimization, Mentorship, AsyncAPI, Software Design, System Design, Data Visualization, Shell Scripting, LDAP, Time Management, Ajax, Deployment, Statistics, WebSockets, Teamwork, Team Leadership, Cross-functional Team Leadership, Ownership, Agile Delivery, Delivery Management, Cost Analysis, API Gateways, Cloudflare, Artificial Intelligence (AI), Agentic AI, Data Analytics, Audits
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