Hire the Best Sinatra Framework Developers in Kyiv, UA

I am a highly experienced full-stack developer with strong knowledge and practical experience in software development on Ruby and Rails web applications. I have over 16 years of experience in software architecture and development in Ruby. Developed a wide range of Ruby and Rails applications in different domains. Worked on server-side back-ends and front-ends as well. Strong analytical and problem-solving skills, always work hard to deliver high-quality and fast results.

Hi, I’m Zlata. I’m basically a typical American Software Engineer... just living in Ukraine now. And I always work in the EST timezone. I’ll write everything in any tech stack you have 😄 I’m a Software Engineer with 8+ years of experience as a Ruby on Rails developer, React developer, Node.js developer, Python developer, and .NET developer. I work with Ruby on Rails, React, Node.js, Python, .NET, PostgreSQL, Docker, AWS, JavaScript, TypeScript, API development, API integration, and SaaS software development. I help companies build and improve SaaS platforms, ERP systems, CRM tools, dashboards, marketplaces, internal systems, API products, and complex web applications using Ruby on Rails, React, Node.js, Python, and .NET. My focus is clean product logic, stable delivery, scalable architecture, and software that stays easy to maintain as the business grows. 📊 My Achievements in Numbers: 🔶 Ruby on Rails Developer for a Construction Application Platform ▪ Helped build a Ruby on Rails + React platform for managing construction applications, reviews, documents, and stakeholder workflows. ▪ Reduced application review time by 42%. ▪ Supported 18,500+ construction applications processed in the first year. ▪ Helped the product reach $1.4M ARR within 14 months. ▪ Worked with Ruby on Rails, React, PostgreSQL, Docker, AWS, S3, and API integration. 🔶 React Developer for a Construction Materials ERP SaaS ▪ Helped improve a complex ERP SaaS platform for concrete, aggregates, and asphalt producers. ▪ Improved sales, pricing, and operational workflows through better product logic and scalable software architecture. ▪ 98% of demo users became clients after product improvements. ▪ 91% of users rated the interface as clear and intuitive. ▪ The product later raised $3.4M. ▪ Focused on React, Ruby on Rails, SaaS workflows, API development, and complex web application structure. 🔶 Node.js Developer for an Aviation Maintenance SaaS ▪ Helped improve a complex aviation maintenance SaaS product used by field teams. ▪ 96% of demo users became clients after the product improvements. ▪ 97% of field users adopted the product after the first try. ▪ Reduced user errors by 41% and made onboarding 62% faster. ▪ Supported product logic, API integration, dashboards, and connected SaaS workflows using Node.js, React, Ruby on Rails, and API development. 🔶 Python Developer for an AI Healthcare SaaS ▪ Supported an AI-powered healthcare platform that grew from a chatbot into multiple AI agents for clinics and hospitals. ▪ The product raised $20M+. ▪ Helped support workflows that increased patient visits by 31%. ▪ Helped reduce call abandonment by 98%. ▪ Worked with Python, API integration, automation workflows, AI-related product logic, and scalable SaaS architecture. 🔶 .NET Developer for a Utility Billing Platform ▪ Helped improve utility billing workflows for a SaaS platform processing complex customer, billing, and reporting data. ▪ Helped process $14M+ in utility bills within 6 months. ▪ Reduced billing cycle time from 9 days to 1.5 days. ▪ Supported 96% client retention through better product stability and workflow clarity. ▪ Worked with .NET, React, API development, reporting logic, SaaS architecture, and reliable software delivery. Why should you hire me as a Software Engineer? ▪ 8+ years of experience with Ruby on Rails, React, Node.js, Python, .NET, JavaScript, TypeScript, PostgreSQL, API development, API integration, and SaaS software development. ▪ 120+ successful projects delivered across B2B SaaS, ERP, CRM, healthcare, construction, logistics, fintech, aviation, and internal business platforms. ▪ Strong experience with Ruby on Rails, React, Node.js, Python, and .NET for SaaS products, dashboards, admin panels, API-first platforms, integrations, automation, AI features, and enterprise systems. ▪ I use Claude, Cursor, GitHub Copilot, and ChatGPT to speed up research, debugging, refactoring, and delivery. ▪ I work well with founders, CTOs, product managers, and teams that need clear communication across Ruby on Rails, React, Node.js, Python, and .NET products. What I can help you with: ✔️ Build or improve Ruby on Rails SaaS products ✔️ Create React dashboards, portals, admin panels, and SaaS interfaces ✔️ Build Node.js services and API integrations ✔️ Support Python automation, data workflows, and product logic ✔️ Work with .NET systems and connected software platforms ✔️ Build API-first products with Ruby on Rails, React, Node.js, Python, .NET, PostgreSQL, Docker, and AWS ✔️ Improve performance, stability, and maintainability of existing Ruby on Rails, React, Node.js, Python, and .NET applications ✔️ Support SaaS, ERP, CRM, fintech, healthcare, logistics, construction, and internal tools Need help with Ruby on Rails, React, Node.js, Python, .NET, API development, or SaaS development? Message me and let’s discuss your product. 📩🤝

Dear Sir/Madam, glad to represent myself! I am a professional Perl programmer with over 20 yrs expertise. The DB used in most of my projects is PostgreSQL, which I work with since 2015 on high-load systems. Last 9 years I had a number of jobs as an architect on full-stack projects based on Perl and sometimes PHP. My strong OOP expertise in Perl covers more than 8 years, using so vanilla Perl as Moose. I am passionate about Perl and I hope I will be useful for your project! The main skills I can offer straight away: Perl (for OOP vanilla Perl and/or Moose, Mojolicious), DBI, PostgreSQL, MySQL/MariaDB, SQL, RESTful API, Perl/PL, Regex, Parsing, Bootstrap, JavaScript, jQuery, Memcached, RabbitMQ, Docker, Wordpress, PHP, Python, Django, LaTex, AWS, GIT, NaturalDocs, Sphinx. Recent most interesting projects are available in the portfolio part on this page for you. I hope to be useful for your project!

⭐⭐⭐⭐⭐"Mykyta has exceptional characteristics both in hard and soft skills. He took a part in complex software development projects as a part of a large mixed group. The feedback from our customers and team is always positive." ⭐I'm the highest-rated and highest-earning Java & Groovy freelancer on Upwork with numerous 5-star reviews, including overly positive feedback. ⭐ I've developed different custom specific software using modern java & groovy software using microservice and monolithic architecture, improved performance, refactored and tested in next business domains: ✅ Utilities ✅ Fintech ✅ Auto ✅ Security ✅ Cryptocurrency ✅✅✅ Brief information about me! ✅✅✅ ✅ Senior Java & Groovy Software Engineer ✅ Specializing in back-end development | Cloud Integrations (AWS, GCP, Azure) ✅ I have over 6.5+ years of experience in Java development ✅ Experienced both in developing software from scratch and maintaining large existing projects ✅ I have hands-on experience in developing back-end web services with micro-service or monolith architecture using Java technology stack, including modern cloud-based solutions. 🌟 WHY YOU SHOULD CHOOSE ME OVER OTHERS? 🌟 ✅ Clients' feedback: I am concentrating on giving VALUE and bringing SUCCESS to all of my customers, earning their TRUST and helping them to EARN MONEY. ALL customers' feedback on my Profile is extremely important to me and proves the value that I provide. ✅ Responsiveness: Communication is extremely important as a part of every business ever existed, and once it is fast and clear, it may lead to awesome results, that's why I tend to be available for my customers in no time, reply fast and clear, as well as I try to be fair, understanding and responsive. ✅ Kindness and Empathy: My main personal principles that I implement in every facet of my life. Treating everyone with respect, aiming to understand the whole situation or problem to solve the pain of my client, and constantly work to IMPROVE the client's product. 🙋🏼‍♂️I am eager to work with you, to provide high-quality code, reliable, consistent solutions, solve your problems and bring success to your business. Contact me, and we will discuss how we can work together to FULLY meet your Business Needs, follow your business rules, and bring you success. A big area of expertise: - REST API design and development - Horizontally scalable and highly available systems - Automating development workflows and deployment pipelines - Micro-service design and development - Design and development of decentralized applications (DApps) - Monitoring, log aggregation - Java and Groovy development - Service-Oriented architecture - Spring Framework (including cloud-based stack) - Experience in NoSQL Development (MongoDB, Neo4j) - Performance and Scalability Optimization Huge Skills & Technologies set: - Java/Groovy - AWS - Linux (with distributives) - Jenkins, CircleCI, Rundeck, Rancher - Docker - MySQL, Postgres - Redis, MongoDB, Neo4j. - RabbitMQ, ActiveMQ, SQS, RabbitMQ

👉 𝗖𝗹𝗶𝗰𝗸 𝗜𝗻𝘃𝗶𝘁𝗲 𝗯𝘂𝘁𝘁𝗼𝗻 𝗼𝗻 𝗺𝘆 𝗽𝗮𝗴𝗲 𝗮𝗻𝗱 𝗹𝗲𝘁'𝘀 𝘁𝗮𝗹𝗸! I'm a Senior Java developer with a solid computer science background and strong analytical, communication, and soft skills. With 14+ years of experience in the financial sector from Fortune 500 list, including working for the largest Swiss investment bank and an Swiss investment fund (as well as for other business domains like Auctions, Consulting etc.), I specialize in delivering high-quality web and enterprise applications tailored to your business needs. 💼 𝗪𝗛𝗬 𝗖𝗛𝗢𝗢𝗦𝗘 𝗠𝗘? – 14+ Years in Finance / Financial / Fintech Development: Extensive expertise in building secure and robust systems for the financial industry. – Full-Stack Proficiency: Skilled in Java, JavaScript, and TypeScript for seamless backend and frontend integration. – Cloud Expertise: Proficient with AWS ( ECS, SQS, SNS, Batch, Lambda, Bedrock, RDS, EC2, CloudWatch, S3 etc.) for scalable cloud solutions. – Comprehensive Technical Leadership: I also manage an Upwork agency, offering access to additional developers to scale your projects as needed. 🚀 𝗪𝗛𝗔𝗧 𝗜 𝗖𝗔𝗡 𝗗𝗢 𝗙𝗢𝗥 𝗬𝗢𝗨: – Custom Software Development: Build scalable, secure, and high-performing web or enterprise applications using Java, Spring, and AWS. – Design & Optimize System Architecture: Design robust and growth-ready systems with cutting-edge technologies. – Front-End Excellence: Create intuitive, user-friendly interfaces using Angular / AngularJS, Vue / Vue JS / Vue.JS, React / React JS / React.JS, Knockout.js. – Cloud Solutions: Implement cloud strategies with AWS services, ensuring cost-efficiency and scalability. – Database Management: Expert in both SQL ( PostgreSQL, MariaDB / MySQL ) and NoSQL ( Apache Cassandra, DynamoDB ) for data-intensive applications. 💪 𝗦𝗞𝗜𝗟𝗟𝗦: Programming Languages: Java 8 / 11 / 17, JavaScript, C/C++, PHP, Bash Frameworks & Libraries: Multithreading, Spring ( SpringBoot, Spring Boot, Spring MVC, SpringMVC, Spring Data, Spring Security ), JPA / Hibernate / Kundera, Akka, JMS ( IBM MQ ), REST, SOAP, Swagger, OpenAPI, REST API, JAX-RS, JAX-WS, AspectJ AOP, Vaadin 7 / 14+ / Flow, JUnit, EasyMock, Solr, Apache POI, JDBC, JSP / JSF, Play Framework, JavaMail, JavaCC, Ehcache Cloud & Infrastructure: AWS: ECS, SQS, SNS, Batch, Lambda, Bedrock, RDS, EC2, CloudWatch, S3, Docker, Hazelcast, Apache ZooKeeper Databases: RDBMS: MS SQL Server, PostgreSQL, MySQL / MariaDB, NoSQL: Apache Cassandra Version Control: Git, SVN, Mercurial Front-End Development: Angular / AngularJS, Ionic, Knockout.js, Vue.js, jQuery, HTML5, CSS, Twitter Bootstrap, Highcharts, Node.js / npm, SockJS / STOMP Build & Automation Tools: Maven, Gradle, Ant Operating Systems: Linux, Windows Cybersecurity: Web-security analysis, symmetric/asymmetric ciphers, PKI Business Domains: Fintech, Banking, Finance, Investment Funds, Payments, Consulting, CRM systems for HR, Car Auctions, Video Streaming 👉 𝗙𝗲𝘄 𝘄𝗼𝗿𝗱𝘀 𝗮𝗯𝗼𝘂𝘁 𝗺𝗲 Fond of developing applications and services using Java Springboot, acting Java backend developer but also as Java Full stack developer. Also I started Upwork agency here and act as PM, feel free to hire more developers if needed! 🎯 𝗟𝗲𝘁'𝘀 𝘀𝗵𝗮𝗽𝗲 𝘆𝗼𝘂𝗿 𝗶𝗱𝗲𝗮 𝗶𝗻𝘁𝗼 𝗮 𝘀𝘂𝗰𝗰𝗲𝘀𝘀𝗳𝘂𝗹 𝗽𝗿𝗼𝗱𝘂𝗰𝘁. Contact me to get started! 📨