Oleksandr Lapchenko
Verified Expert in Engineering
Full-stack Engineer and Developer
Lisbon, Portugal
Toptal member since October 24, 2024
Oleksandr is a product-driven full-stack engineer with 10 years of tech experience and a keen interest in AI technologies. He specializes in building and scaling customer-facing products and leading distributed teams. Proficient in TypeScript, React, and Ruby on Rails, he has built great products for Toptal and Heartland Retail. Oleksandr has a proven track record of delivering high-impact solutions and managing production environments with a focus on reliability, performance, and security.
Portfolio
Experience
- Ruby - 10 years
- JavaScript - 10 years
- PostgreSQL - 10 years
- Software Architecture - 5 years
- React - 5 years
- TypeScript - 3 years
- People Management - 3 years
- Next.js - 2 years
Availability
Preferred Environment
MacOS, Slack, Zoom, Visual Studio Code (VS Code), Cursor AI
The most amazing...
...thing I've done is coordinate and help build multiple internal systems for Toptal Core, which transformed its business and ensured its competitive edge.
Work Experience
Engineering Manager
Toptal
- Developed and deployed a scalable analytics engine using BigQuery and Next.js, centralizing 120+ data points and prioritizing 25 marketing activities for all marketing departments.
- Headed the development of a new client retention offering, enhanced market positioning, and achieved a customer satisfaction rating of 4.95.
- Joined and led the Next.js team, ensuring smooth delivery and improving key processes without prior framework expertise in delivering mission-critical initiatives.
- Established incident resolution and on-call processes, achieving 100% service-level agreement (SLA) compliance and zero escalated issues during a 90-day window.
- Transitioned the team from Kanban to Scrum, improving planning accuracy by 30%.
- Coordinated systematic technical debt reduction, upgrading Next.js 12 to 14, increasing test coverage from 41.5% to 68.8%, doubling sync job speed, and enhancing system reliability.
- Collaborated with product managers to align technical solutions with business objectives, resulting in more accurate project timelines and enhanced product-market fit.
- Facilitated team development by promoting two members, implementing a career skills map, and providing targeted coaching, resulting in improved skill alignment and career growth opportunities.
- Oversaw technical recruitment and onboarding efforts, hiring two engineers, onboarding five team members across two teams over two years, and enhancing overall team capabilities at Toptal.
Senior Back-end Developer
Toptal
- Headed successful strategic project development from an MVP to the first release in Q4 2021. Started to lead the initiative three weeks after joining. Prepared 90% of back-end tickets and organized the work of six engineers.
- Architected and delivered an enterprise-level solution to expand company offerings, implementing one-time consultations from talents to clients. Built a production-quality system integrated with other services using Kafka and GraphQL API.
- Built a CI pipeline with testing and linting using GitHub Actions. The app was deployed in Kubernetes.
- Received recognition for the most completed tickets two times among team members.
Senior Software Developer
Heartland Payment Systems
- Helped the team deliver a new version of the POS system, which was rewritten on React Native and GQL. Owned and developed a few critical flows end-to-end, such as refunds and returns for the latest version of POS.
- Wrote a custom N+1 matcher for the Sequel library, allowing the team to perform new testing and ensure that app performance stayed the same.
- Restructured the teamwork schedule by transitioning the sprint cycle from Monday to Friday to Wednesday to Tuesday. This adjustment eliminated late Friday deployments, minimized task wait times, and enhanced the product planning process.
Team Lead
Cropwise Operations
- Spearheaded the project that transformed the company from a SaaS solution to a platform, overseeing the process from ideation to launch.
- Built a platform that integrated over 15 data providers with a team of three developers over nine months.
- Mentored two developers, guiding them from junior roles to achieving mid-level engineering proficiency.
- Developed a machine learning (ML) R&D model to compute normalized difference vegetation index (NDVI) from radio satellite images.
- Designed and built a tool for planning complex agronomic application tasks in four months. The project opened new markets for the company.
- Optimized the back end for processing real-time fleet data. Architected scalable and effective systems for business requirements. Achieved speed-up from 10 req/sec to 1,000 req/sec.
- Organized internal meetups to share experiences and best practices.
Experience
SaaS for Agriculture
Heartland Retail
Internal System for SEO Monitoring
I coordinated this project in a cross-functional environment, set business requirements and estimated costs, and helped develop and test it. It ended with great success. We were able to cover around 500 pages, and it provided daily monitoring of the SERP position.
Education
Master's Degree in Computer Science
Taras Shevchenko Kyiv Nation University - Kyiv, Ukraine
Skills
Libraries/APIs
Node.js, React, REST APIs, React Native for Web, jQuery, GraphQL API, Sequel, Leaflet
Tools
Slack, Ahrefs, Git, Amazon Simple Queue Service (SQS), BigQuery, Zoom, Prisma, RSpec, GIS
Languages
Ruby, TypeScript, JavaScript, GraphQL, HTML, CSS, Python, Java, C++
Frameworks
Next.js, Ruby on Rails (RoR), Bootstrap, Flask, Material UI, Ruby on Rails 6, Ruby on Rails 5, React Native
Paradigms
Agile, ETL, Event-driven Architecture, DevOps, Mobile Development, Continuous Delivery (CD), Continuous Integration (CI)
Platforms
MacOS, Vercel, Amazon Web Services (AWS), AWS Lambda, Visual Studio Code (VS Code), Web, Kubernetes, Apache Kafka, Mapbox
Storage
PostgreSQL, Database Architecture, Databases, Google Cloud, MariaDB, Redis Cache, NoSQL, Redis
Other
Software Architecture, Artificial Intelligence (AI), People Management, Architecture, Planning, APIs, Minimum Viable Product (MVP), MVP Design, Full-stack, CTO, Fractional CTO, Estimations, Web App Development, Technical Leadership, Full-stack Development, CI/CD Pipelines, Solution Architecture, Real-time Data, Scrum Master, Proof of Concept (POC), Text to Speech (TTS), Prototyping, Streaming, Cursor AI, Data Analytics, Optical Character Recognition (OCR), Computer Science, Algorithms, Informatics, Discrete Mathematics, Budgeting, Performance, Leadership, Interpersonal Skills, Specs, Distributed Team Management, Distributed Systems, Cross-functional Team Leadership, BullMQ, Coaching, Mentorship, Talent Management, Tools, SEO Tools, Communication, Engineering Management, Engineering, Hands-on Implementation, Data Engineering, Timelines, Code Review, Quality Assurance (QA), Enterprise SaaS, Charts
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