Lukas Liesis
Verified Expert in Engineering
JavaScript Developer
Vilnius, Vilnius County, Lithuania
Toptal member since May 6, 2016
Lukas is an elite software engineer for founders, building stable, high-value SaaS products. He partners directly with founders and CEOs to transform business visions into high-value, stable, and user-centric applications. Lukas is a skilled developer with 20 years of experience on projects with up to 15 million users and $1.5 billion annually. He is a problem-solver first, an engineer second.
Portfolio
Experience
- RESTful Development - 15 years
- JavaScript - 15 years
- REST APIs - 15 years
- Node.js - 12 years
- React - 8 years
- Google Material Design - 7 years
- WebSockets - 7 years
- MongoDB - 6 years
Preferred Environment
React, Node.js, TypeScript, Amazon Web Services (AWS), Full-stack, OpenAI API, OpenAI, Gemini, Next.js, Stripe, ChatGPT API, AI Automation, CRM Design, FastAPI, Python, Figma to React, REST, AI-generated Code, Large Language Models (LLMs), Software Architecture, PostgreSQL, Microfrontends, Team Leadership, Debugging, CTO, Webhooks, Technical Leadership, RESTFul APIs, Kubernetes, Claude, Codex, Cursor AI, Infrastructure as a Service (IaaS), Database Design, Docker
The most amazing...
...thing I've built was in cooperation with ex-Googlers and scientists from NASA. It was part of a core for services used by 15+ million users globally.
Work Experience
Full-stack Node.js and React Developer
Metara Inc
- Built the platform from idea to MVP. It enables educators to create Bloom’s taxonomy-based, AI-driven knowledge notes, and allows students to engage in AI-driven learning or exam sessions.
- Used Cursor IDE, Claude Code, Codex, and Wispr to deliver the platform in record time.
- Developed Kubernetes infrastructure, data access patterns, data pipelines, and an AI-driven development pipeline and edtech readiness solution.
Interim Chief Technology Officer
Encargogo
- Helped with the early stage of the https://encargogo.com/en.
- Developed strategies and tech stack, onboarded devs, and coded a big portion of core code.
- Led integrations with shipment partners and helped talk with investors.
Senior Full-stack Developer
ProSchoolPublisher
- Investigated legacy infrastructure and code with the founder, designed the full upgrade, and executed it.
- Developed full test-driven back-end APIs, DevOps infrastructure, and UI development with React.
- Delivered at a high pace using modern AI coding tools such as Cursor IDE, Claude Code, Codex, Open Code, Wispr Flow, and WebStorm.
Lead Project Engineer
Rayna Tours
- Helped develop processes and systematize these visions. A $250 million/year company had an internal ambition to reshape the technical side of it and explore how it could do better.
- Built tech processes and dev teams, as well as trained, mentored, and worked closely with other PMs, designers, and managers.
- Developed new ways to achieve the complex goals of Rayna.
Technical Lead
TradeCafe
- Handled all technical infrastructure and integrations.
- Worked directly with CTO, dev teams, leads, and product managers.
- Re-invited to the company after 4-5 years of break for the scaling stage.
CTO and Co-founder
LittleSaas, Inc.
- Landed as a CTO at Little SaaS, Inc. after building startups with the best talent from Google, NASA, and other places. Had to build remote dev teams, find talent, train, and deliver tech.
- Built from the ground up a SaaS marketplace and many sales-related solutions.
- Helped other founders and startups to grow, advised from a technical standpoint, and mentored many people.
Chief Technology Officer (CTO)
FirstSales.io
- Built, managed, onboarded, trained, and hired an entire development team.
- Built a cold email outreach tool. Did all full-stack core solo, then later onboarded developers for the back end and front end.
- Did all infrastructure DevOps for a startup in cold email outreach.
- Used early-stage AI models to create contextual individual ice-breaking lines for each lead in an email campaign.
Lead Back-end Engineer
TradeCafe
- Built all the foundation back end before going live for the marketplace, which now runs at a volume of 1.5 billion a year.
- Built integrations, code structure, and server DevOps for the launch when the marketplace was at the idea stage, up to the production environment.
- Onboarded two dev leads to the company, who, to this day (seven years later), are leading core parts of the marketplace.
- Was re-invited by the CTO to lead infrastructure and integration teams during the scale phase once the marketplace was ±6 years old.
Front-end Software Engineer
Pace
- Solo-built specialized demos with React, from idea to production.
- Worked directly with founders who were an ex-Googler and a NASA scientist.
- Got excellent feedback on my LinkedIn and other profiles.
Lead Software Engineer
Wristband E-shop
- Developed a single-page site to choose, order, and follow orders. Integrated with payment APIs.
- Built the full stack solely from idea to production—DevOps, APIs, and UX.
- Worked directly with the founder to translate business goals into technical solutions and implemented them on my own.
React Developer
ArcChat.com
- Took on a full-stack challenge to minimize this site's technology stack down to one programming language (JavaScript). JS is used all the way through, from server to client and database and even for most CSS. I also used material-design specifications to create an easy-to-use UI. With React.js, I was so much more productive than with PHP's MVC style frameworks. It was a pleasure to move out of PHP world.
- Completed the project solo in three months.
- Built a native Android app with React.
Android Developer (React Native)
LHM Group
- Built a React Native app for Android where you can preview a house project and order from LHM. The challenge was to build a React Native app for Android while it was released only for 1-2 weeks for public usage outside of Facebook.
Core Software Engineer
Hostinger International
- Hired as 5th engineer at Hostinger to help develop the Hostinger and Youhosting network (15,000,000+ users) with Zend Framework and Doctrine. Handled full-stack, back-end, and front-end development.
- Developed internal software for users, staff members, and invoice management.
- Revised and optimized the main home page, which is now Hostinger.com. It was a white-label solution for all localized services, which later evolved to a combined Hostinger.com.
- Created an invoice management system for internal usage from the ground up. Added numerous new features to Hostinger's network management system.
Developer/SEO Consultant/Freelancer
VEGE
- Built VEGE.ru's website. It is an official VEGE website to represent the company for clients from Russia, Ukraine, and other Russian speakers.
SEO Consultant, Freelancer for eCommerce
Metalo Amžius
- Improved SEO to increase online sales. Remade the administration panel to make it easier to use. Taught administrators to use the CMS. Made all required updates to content, layout, etc.
- Used PrestaShop to do the biggest part of the job.
- Synced the item status with old software that manages item availability.
Experience
Trafikito.com
It's a command output monitoring service deployed on high-quality, global AWS Infrastructure—three edges, global DB tables, and load balancing.
Free-Templates.lt
Squirrel-Host.com
News-Flow
Manualai.lt
AutoMouser
Gerda Photography
We are devoted to feelings, emotions, and real life. People love our photographs because of the cosiness, lighting, and authentic decorations. Our photography is 70% psychology, 20% design, and 10% technique.
React Examples Repository
https://github.com/liesislukas/ReactJs-boilerplate-and-examplesLukasliesis.com
https://lukasliesis.com/Otelic
https://otelic.com/Oisie
Leadpurify.com
Education
Master's Degree in Physics (Environmental Management)
Vytautas Magnus University - Lithuania
Secondary B.S. Studies Degree in Business and Applied Informatics
Vytautas Magnus University - Lithuania
Bachelor of Science Degree in Physics (Energetic)
Vytautas Magnus University - Lithuania
Skills
Libraries/APIs
Node.js, REST APIs, jQuery, React, OpenAI API, Stripe, React Query, Playwright, SendGrid API, PayPal API, Twilio Sync API, Amazon EC2 API, Back-end APIs, Puppeteer, Antd, Claude API
Tools
GitHub, Git, Adobe Photoshop, Adobe Lightroom, NGINX, RabbitMQ, SendGrid, Claude, Codex, TanStack Router, Apache, PrestaShop, Adobe Illustrator, Amazon EKS, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), AWS IAM, PM2, Amazon CloudFront CDN, Amazon Simple Email Service (SES), Lighthouse, AI Prompts, Prettier, Auth0, Claude Code
Languages
JavaScript, CSS, SQL, HTML, TypeScript, HTML5, PHP, GraphQL, Python
Frameworks
Material UI, Flux, Next.js, Express.js, Tailwind CSS, React Native, Zend Framework, .NET, Fastify, Redux
Paradigms
RESTful Development, Database Design, REST, Microservices, B2B, Role-based Access Control (RBAC), Unit Testing, HIPAA Compliance, Microfrontends, Serverless Architecture, Model Context Protocol (MCP), DevOps, UX Design, Business Intelligence (BI), Scalable Application, Back-end Architecture, API-first Development, Hosting
Platforms
MacOS, Amazon Web Services (AWS), Docker, Kubernetes, AWS Lambda, Apache Kafka, Joomla, Firebase, Amazon EC2, AWS NLB, Hostinger, Typesafe, Google Cloud Platform (GCP)
Storage
MySQL, Redis, PostgreSQL, Amazon DynamoDB, MongoDB, Elasticsearch, ClickHouse Cloud, Amazon S3 (AWS S3), Data Pipelines, ClickHouse, Google Cloud
Other
Google Material Design, WebSockets, Freelancing, Full-stack, API Integration, CI/CD Pipelines, Full-stack Development, Data Engineering, ChatGPT API, AI Automation, CRM Design, Figma to React, AI-generated Code, Large Language Models (LLMs), Software Architecture, Minimum Viable Product (MVP), Consulting, Debugging, CTO, Webhooks, Headless CMS, Technical Leadership, RESTFul APIs, Agentic AI, ESLint, Ubuntu Server, Usability, SVG, Front-end, Serverless, Artificial Intelligence (AI), Enterprise Resource Planning (ERP), UI Testing, General Data Protection Regulation (GDPR), AI Integration, User Experience (UX), System Design, Team Leadership, HIPAA Electronic Data Interchange (EDI), Legacy Code, Cursor AI, Infrastructure as a Service (IaaS), Amazon API Gateway, LLM Integration, AI Agent Orchestration, Material Design, Virtual Private Servers, Gemini API, OpenAI, Gemini, Problem Management, Problem Structuring, Information Technology, Software Engineering, IT Projects, Execution, Project Planning, Business Development, Technical Hiring, Integration, Product Management, Amazon Kinesis, AWS Auto Scaling, Tailwind UI, Physics, Article Writing, Servers, API Design, DSLR Photography, Communication, Documentation, Front-end Development, APIs, AI Agents, Web Crawlers, Content Delivery Networks (CDN), Authentication, Authorization, Scalable Platforms, Web Scraping, Website Data Scraping, Scalable Architecture, Scalable Web Services, Platforms, Containerization, Containers, Back-end, Back-end Development, Back-end Performance, Back-end Admin Systems, SaaS, Startups, Lean Startups, eCommerce, eCommerce UI, eCommerce UX, eCommerce APIs, Mobile eCommerce, eCommerce CMS, eCompliance, Server-side Rendering (SSR), SEO Tools, User Interface (UI), ChatGPT Prompts, Prompt Engineering, Large-scale Web Crawlers, Proxies, Web Marketing, B2C Marketing, SEO Marketing, AI Marketing, Lead Marketing, Drip Marketing, Bulk Marketing, Deal Marketing, OpenTelemetry, Data Aggregation, Message Queues, Finance, SOC 2, FastAPI, Engineering, DevOps Engineer, Test Engineering, UX Engineering, UI Engineering, Sales Engineering, Cloud Engineering, Supabase, Legacy Software, Education, K-12 Education, Builder, Drag & Drop
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
Share your needs
Choose your talent
Start your risk-free talent trial
Top talent is in high demand.
Start hiring