Lukas is available for hire
Hire LukasLukas Liesis
Verified Expert in Engineering
JavaScript Developer
Vilnius, Vilnius County, Lithuania
Toptal member since May 6, 2016
Bio
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
Metara Inc
Node.js, HTML, JavaScript, React, Next.js, Large Language Models (LLMs), Auth0...
Encargogo
Node.js, MongoDB, DevOps, Amazon S3 (AWS S3), UX Design, React, Next.js...
ProSchoolPublisher
TypeScript, Legacy Code, Legacy Software, Education, K-12 Education, Builder...
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
Work Experience
Full-stack Node.js and React Developer
2025 - 2026
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.
Technologies: Node.js, HTML, JavaScript, React, Next.js, Large Language Models (LLMs), Auth0, Headless CMS, PostgreSQL, Supabase, Database Design, Docker, CI/CD Pipelines, HIPAA Compliance, TanStack Router, LLM Integration, Agentic AI, AI Agent Orchestration, Model Context Protocol (MCP), Role-based Access Control (RBAC), Agentic Coding, Leadership, Systems Design, Startups, Vibe Coding, Claude Code
Interim Chief Technology Officer
2025 - 2025
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.
Technologies: Node.js, MongoDB, DevOps, Amazon S3 (AWS S3), UX Design, React, Next.js, Communication, Documentation, Front-end, Front-end Development, AWS IAM, AI Agents, OpenAI, OpenAI API, Gemini, Web Crawlers, Amazon CloudFront CDN, Content Delivery Networks (CDN), Authentication, Authorization, Scalable Platforms, Web Scraping, Website Data Scraping, Back-end, Back-end APIs, Back-end Development, Back-end Performance, Back-end Architecture, Back-end Admin Systems, eCommerce UI, eCommerce UX, eCommerce APIs, Mobile eCommerce, CI/CD Pipelines, Server-side Rendering (SSR), User Interface (UI), SEO Tools, Artificial Intelligence (AI), AI Prompts, ChatGPT Prompts, Prompt Engineering, ESLint, Prettier, Puppeteer, Large-scale Web Crawlers, Proxies, Stripe, REST APIs, Full-stack Development, Finance, Freelancing, HTML, TypeScript, Full-stack, Tailwind CSS, React Query, Data Engineering, ChatGPT API, AI Automation, CRM Design, API Integration, Figma to React, REST, AI-generated Code, Large Language Models (LLMs), Software Architecture, Microservices, AI Integration, B2B, Minimum Viable Product (MVP), Consulting, System Design, Team Leadership, Amazon Web Services (AWS), Debugging, CTO, Webhooks, Technical Leadership, RESTFul APIs, Database Design, Redis, Docker, TanStack Router, LLM Integration, Agentic AI, AI Agent Orchestration, Model Context Protocol (MCP), Role-based Access Control (RBAC), Agentic Coding, Leadership, Systems Design, Affiliate Marketing, Marketplaces, Payment Gateways, Startups, Vibe Coding, Claude Code
Senior Full-stack Developer
2024 - 2025
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.
Technologies: TypeScript, Legacy Code, Legacy Software, Education, K-12 Education, Builder, React, React Query, Drag & Drop, AI Agents, Cursor AI, Codex, Claude Code, Claude API, Claude, Database Design, Docker, CI/CD Pipelines, TanStack Router, Agentic AI, AI Agent Orchestration, Role-based Access Control (RBAC), Agentic Coding, Leadership, Systems Design, Payment Gateways, Startups, Vibe Coding
Lead Project Engineer
2024 - 2025
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.
Technologies: IT Projects, Execution, Project Planning, Business Development, Technical Hiring, Next.js, React, Database Design, DevOps, TypeScript, Communication, APIs, Business Intelligence (BI), Amazon CloudFront CDN, Scalable Platforms, Scalable Architecture, Back-end, Back-end APIs, Back-end Development, Back-end Architecture, Back-end Admin Systems, Scalable Application, eCommerce, eCommerce UI, eCommerce UX, eCommerce APIs, eCommerce CMS, CI/CD Pipelines, Server-side Rendering (SSR), Lighthouse, SEO Tools, User Interface (UI), REST APIs, Full-stack Development, Enterprise Resource Planning (ERP), Finance, Freelancing, HTML, Full-stack, React Query, Data Engineering, CRM Design, API Integration, Figma to React, REST, Software Architecture, Microservices, PostgreSQL, AI Integration, B2B, Minimum Viable Product (MVP), Consulting, User Experience (UX), Front-end, System Design, Team Leadership, Amazon Web Services (AWS), Debugging, Webhooks, Headless CMS, Technical Leadership, RESTFul APIs, Legacy Code, Docker, Role-based Access Control (RBAC), Leadership, Systems Design, Payment Gateways
Technical Lead
2024 - 2024
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.
Technologies: Node.js, Integration, Express.js, MongoDB, Redis, Kubernetes, Amazon EKS, Scalable Platforms, Scalable Application, Scalable Architecture, Scalable Web Services, AWS IAM, AWS NLB, Amazon S3 (AWS S3), Amazon EC2, Amazon EC2 API, DevOps, Platforms, Authentication, Authorization, API Design, Docker, Containerization, Containers, Data Pipelines, Back-end, Back-end Performance, Back-end Architecture, Back-end Development, Back-end Admin Systems, Back-end APIs, APIs, API-first Development, REST APIs, eCommerce, eCommerce CMS, eCommerce APIs, eCompliance, CI/CD Pipelines, Enterprise Resource Planning (ERP), Freelancing, HTML, TypeScript, Data Engineering, CRM Design, API Integration, REST, Software Architecture, RabbitMQ, Apache Kafka, Elasticsearch, Microservices, AI Integration, B2B, Front-end, System Design, Team Leadership, Amazon Web Services (AWS), Debugging, HIPAA Compliance, HIPAA Electronic Data Interchange (EDI), Google Cloud, Webhooks, Technical Leadership, RESTFul APIs, Legacy Code, Infrastructure as a Service (IaaS), AWS Lambda, Database Design, Python, Role-based Access Control (RBAC), Systems Design, Marketplaces, Payment Gateways
CTO and Co-founder
2019 - 2024
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.
Technologies: Engineering, Data Engineering, DevOps Engineer, Test Engineering, UX Engineering, UI Engineering, Prompt Engineering, Sales Engineering, Software Engineering, Cloud Engineering, TypeScript, Node.js, React, Next.js, Tailwind CSS, CTO, SendGrid API, SendGrid, Webhooks, Headless CMS, Technical Leadership, RESTFul APIs, Serverless, AWS Lambda, Amazon API Gateway, Serverless Architecture, Database Design, Redis, Docker, CI/CD Pipelines, Role-based Access Control (RBAC), Leadership, Systems Design, Affiliate Marketing, Marketplaces, Payment Gateways, Startups, eCommerce
Chief Technology Officer (CTO)
2022 - 2023
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.
Technologies: Node.js, Fastify, MongoDB, Amazon DynamoDB, Redis, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), Amazon S3 (AWS S3), Product Management, Technical Hiring, REST APIs, Servers, Serverless, AWS Lambda, Amazon Simple Email Service (SES), Scalable Platforms, Scalable Application, Scalable Web Services, Scalable Architecture, SaaS, Startups, Lean Startups, CI/CD Pipelines, Server-side Rendering (SSR), Web Marketing, B2C Marketing, SEO Marketing, AI Marketing, Lead Marketing, Drip Marketing, Bulk Marketing, Deal Marketing, Stripe, Full-stack Development, Freelancing, HTML, TypeScript, Full-stack, Tailwind CSS, React Query, UI Testing, Playwright, OpenAI API, ChatGPT API, AI Automation, API Integration, Figma to React, REST, AI-generated Code, Large Language Models (LLMs), Software Architecture, Microservices, PostgreSQL, AI Integration, B2B, Minimum Viable Product (MVP), User Experience (UX), Front-end, System Design, Team Leadership, Amazon Web Services (AWS), Debugging, CTO, SendGrid API, SendGrid, Webhooks, Headless CMS, Technical Leadership, RESTFul APIs, Amazon API Gateway, Serverless Architecture, Database Design, Docker, LLM Integration, Role-based Access Control (RBAC), Systems Design, Affiliate Marketing, Payment Gateways
Lead Back-end Engineer
2017 - 2019
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.
Technologies: Node.js, Express.js, DevOps, AWS IAM, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), Amazon S3 (AWS S3), Amazon Kinesis, Amazon EC2, Amazon EC2 API, AWS Auto Scaling, PM2, TypeScript, JavaScript, API Integration, eCommerce, eCommerce CMS, eCommerce APIs, eCompliance, Mobile eCommerce, CI/CD Pipelines, REST APIs, Enterprise Resource Planning (ERP), Finance, Freelancing, HTML, GraphQL, CRM Design, REST, Software Architecture, Apache Kafka, Elasticsearch, Microservices, B2B, Minimum Viable Product (MVP), Front-end, System Design, Team Leadership, Amazon Web Services (AWS), Debugging, Google Cloud Platform (GCP), Webhooks, Technical Leadership, RESTFul APIs, Legacy Code, Database Design, Redis, Docker, HIPAA Compliance, Role-based Access Control (RBAC), Marketplaces, Payment Gateways, Startups
Front-end Software Engineer
2016 - 2017
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.
Technologies: React, Redux, JavaScript, eCommerce, eCommerce UI, eCommerce UX, Mobile eCommerce, Stripe, Freelancing, HTML, UI Testing, CRM Design, API Integration, Figma to React, REST, Software Architecture, User Experience (UX), Front-end, Microfrontends, Amazon Web Services (AWS), Debugging, RESTFul APIs, Firebase, Payment Gateways, Startups
Lead Software Engineer
2016 - 2016
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.
Technologies: Material UI, Firebase, React, CSS, HTML5, Express.js, eCommerce, eCommerce UI, eCommerce UX, eCommerce APIs, Mobile eCommerce, Stripe, REST APIs, Full-stack Development, Freelancing, HTML, Full-stack, CRM Design, Figma to React, REST, Software Architecture, User Experience (UX), Front-end, Microfrontends, Debugging, RESTFul APIs, Database Design, Payment Gateways, Startups
React Developer
2015 - 2016
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.
Technologies: WebSockets, REST APIs, RESTful Development, Git, PayPal API, MongoDB, NGINX, Material Design, Node.js, React Native, React, CSS, HTML5, Full-stack Development, Freelancing, HTML, JavaScript, Full-stack, Software Architecture, User Experience (UX), Front-end, RESTFul APIs, Database Design, Firebase
Android Developer (React Native)
2015 - 2015
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.
Technologies: React Native, CSS, Express.js, Freelancing, Legacy Code
Core Software Engineer
2012 - 2015
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.
Technologies: RESTful Development, REST APIs, Zend Framework, PHP, MySQL, JavaScript, HTML5, Scalable Platforms, Hosting, Hostinger, eCommerce, eCommerce CMS, eCommerce APIs, CI/CD Pipelines, Stripe, Full-stack Development, HTML, Full-stack, CRM Design, Software Architecture, Legacy Code, Database Design, Payment Gateways
Developer/SEO Consultant/Freelancer
2012 - 2013
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.
Technologies: PHP, SQL, Apache, Joomla, HTML5, Freelancing, HTML, JavaScript, Legacy Code, Payment Gateways
SEO Consultant, Freelancer for eCommerce
2011 - 2013
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.
Technologies: Virtual Private Servers, Twilio Sync API, PrestaShop, HTML5, Freelancing, HTML, JavaScript
Project History
Trafikito.com
I always wanted to monitor the output of any command. With Trafikito, I can. It monitors the output of any command and executes an API call when specific events occur.
It's a command output monitoring service deployed on high-quality, global AWS Infrastructure—three edges, global DB tables, and load balancing.
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
A fully automatic website with pre-made content. This system has tens of thousands of templates ready to publish. The system grabs a template archive, analyzes it, makes some changes, and publishes. It has search by hue.
Squirrel-Host.com
Squirrel-Host.com is a hosting solution. Here, you can register a free account and get hosting for your website. Check out all the great features on the Squirrel-Host.com page.
News-Flow
What was challenging in this project was the amount of data. I developed a crawler that collected news from around the net and published it on a news-flow site. I used a SQL database and built a full aggregation pipeline for a news network-type SaaS.
Manualai.lt
Manualai.it is an educational project to help people in Lithuania learn about IT. There are several connected sites with articles about coding, design, and a forum for help and support. I contributed to Joomla, SMF forum, and some custom components for those systems.
AutoMouser
Built with the C family. I needed an auto mouse clicker and didn't find exactly what I was looking for, so I learned some .NET code and made it myself. It was my second app with the .NET Framework and C family languages. It was interesting to move out of my comfort zone of web development and try building something for the Windows OS. AutoMouser is quite a popular tool now, with roughly 1,500 weekly downloads.
Gerda Photography
I, along with my wife, organize professional photo shoots. We shoot private sessions or big events.
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.
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-examplesA GitHub repository where I create example apps with React. By teaching, we learn. I built a full app boilerplate and also multiple samples for the React Native touch demo, buttons, isomorphic router patterns, and more.
Lukasliesis.com
https://lukasliesis.com/My personal website. It was built with React and NextJS, hosted on a custom server inside Kubernetes. I did everything from DevOps to UX. It's there to showcase my profile and key highlights, my stance on AI, my articles, and labs.
Otelic
https://otelic.com/A platform built on top of the OpenTelemetry open-source standard. It receives telemetry data, allowing developers to browse and analyze application behavior through a clean web interface. I built it all from DevOps to back-end APIs and UI/UX. It uses MongoDB as its primary data source and ClickHouse for logs and traces.
Oisie
A system where developers define events, and marketers build automation flows. It can send targeted emails or trigger webhooks based on what users do (or don't do). I used MongoDB, Node.js, Redis, TypeScript, and React. I built it all from DevOps to UI and APIs.
Leadpurify.com
A service where users upload a CSV of contacts. The back end parses data, extracts social links, performs live SMTP checks to verify each email address, and returns a clean, verified file. I did it all, from DevOps to UI.
Education
2012 - 2014
Master's Degree in Physics (Environmental Management)
Vytautas Magnus University - Lithuania
2010 - 2012
Secondary B.S. Studies Degree in Business and Applied Informatics
Vytautas Magnus University - Lithuania
2008 - 2012
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, Claude Code, 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
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, Startups, 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, Agentic Coding, Leadership, Systems Design, Affiliate Marketing, Marketplaces, Payment Gateways, Vibe Coding, ESLint, Ubuntu Server, Usability, SVG, Front-end, Serverless, eCommerce, 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, Lean Startups, 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
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