Vytautas is available for hire

Vytautas Saulis

Verified Expert in Engineering

OpenAI GPT-4 API Developer

Vilnius, Vilnius County, Lithuania

Toptal member since February 14, 2022

Expertise

Software Development Full-stack Front-end Back-end Developers C#JavaScript PHP Agile Development Jira Slack Development CSS HTML5 Database React.js

Bio

Vytautas is a full-stack software developer passionate about security, good code quality, and best practices. His experience covers the banking, insurance, eCommerce, and data security industries. He has developed systems for inventory management, a self-sovereign identity wallet, and design improvements for Amerant Bank. Vytautas enjoys staying up-to-date with fast-changing technologies.

Portfolio

Checkmate.com Inc.

React, React Native, TypeScript, Redux, Emotion Library, React Router...

Ondato

TypeScript, React Native, React Navigation, Styled-components, SDKs, Figma...

Atobi

TypeScript, React Native, Expo, React Query, React, Jest, Jira, Slack, Expo.io...

Experience

C# - 7 years
.NET Core - 6 years
TypeScript - 6 years
React - 6 years
React Native - 5 years
Node.js - 5 years
Blockchain - 4 years
OpenAI GPT-4 API - 1 year

Availability

Part-time

Preferred Environment

Windows, Slack, Skype, Jira, Bitbucket, GitLab, GitHub, Microsoft Teams, Trello

The most amazing...

...tool I've developed is a multi-vendor eCommerce application.

Work Experience

React Senior Developer

2024 - 2025

Checkmate.com Inc.

Developed interactive pizza builder functionality for both mobile and web applications.
Managed 20+ branded React websites using a shared codebase.
Managed 20+ branded React Native apps using a shared codebase.
Implemented CI/CD pipelines for React Native projects using Fastlane.
Implemented Freedom pay integration in both mobile and web.
Integrated Freedom Pay into both mobile and web platforms.
Implemented ADA compliance for React websites, ensuring accessibility standards and best practices.
Optimized performance for large menus with over 300 items, enhancing load times and responsiveness.

Technologies: React, React Native, TypeScript, Redux, Emotion Library, React Router, React Navigation, Google Maps, Apple Pay, Google Pay, CircleCI, Sentry

Senior React Native Developer

2022 - 2023

Ondato

Engineered a React Native SDK for Ondato's identity verification, facilitating the effortless infusion of state-of-the-art services into mobile applications.
Executed sophisticated biometric authentication functionalities, amplifying security measures and user interaction quality for clients.
Enriched developer documentation and support assets, resulting in elevated community participation and heightened developer contentment.
Guided a team of three members in establishing and maintaining the Ondato SDK React Native repository. Nurtured collaborative efforts, set objectives, advocated best practices, resolved conflicts, and ensured prompt deliverables.

Technologies: TypeScript, React Native, React Navigation, Styled-components, SDKs, Figma, Redux, Redux Thunk, React, React Redux, React Query, APIs, Jira, Slack, Android, iOS, Swift, Kotlin, Firebase, Jest, FaceTec, Front-end

Senior Front-end Developer

2019 - 2023

Atobi

Delivered exceptional software solutions that met project requirements and surpassed client expectations, consistently achieving high-quality results.
Implemented Agile development methodologies to boost productivity and adaptability, resulting in the timely completion of projects according to schedule.
Consistently elevated coding practices and upheld codebase integrity, ensuring both scalability and simplified maintenance for long-term sustainability.
Demonstrated seamless collaboration with cross-functional teams, facilitating the integration of design, development, and testing efforts for streamlined and efficient project outcomes.

Technologies: TypeScript, React Native, Expo, React Query, React, Jest, Jira, Slack, Expo.io, Tailwind CSS, iOS, Android, Azure, Node.js, Figma, CI/CD Pipelines, Redux, React Redux, JavaScript, Agile, CSS, HTML, HTML5, SCSS, Firebase, Sentry, Front-end, Next.js, WYSIWYG Web Builders

Senior Full-stack Developer

2020 - 2021

Nano Bitas

Implemented a complex microservices architecture using domain-driven design principles, resulting in improved response times and reduced error rates compared to the previous monolithic structure.
Led the migration of a legacy system to a modernized C# codebase, enhancing code maintainability and reducing bug reports from quality assurance.
Managed a cross-functional team of two developers, promoting collaboration and knowledge sharing within the group. Achieved increased team productivity and improved code quality metrics over a 6-month period through mentoring and code reviews.
Established an automated deployment pipeline using continuous integration and continuous deployment (CI/CD) practices, reducing deployment errors and accelerating feature delivery to production, leading to heightened customer satisfaction.

Technologies: C#, TypeScript, Redux, Redux Thunk, React, Agile, React Redux, React Query, APIs, Jira, Full-stack Development, Full-stack, Back-end, Slack, Jest, C#.NET, .NET, .NET Core, AutoMapper, Domain-driven Design (DDD)

Senior React Developer

2020 - 2021

Luminor

Created an expansive and adaptable React component library utilizing TypeScript for Luminor Back, cultivating uniform design principles and seamless integration capabilities.
Achieved exceptional performance and responsiveness by implementing optimized coding techniques, resulting in a frictionless user experience.
Emphasized modularity and configurability, empowering convenient customization of components and amplifying developer efficiency.
Offered comprehensive documentation and robust community assistance, culminating in heightened adoption rates and substantial achievements within the developer community.

Technologies: TypeScript, React, Jest, Jira, Slack, HTML, CSS, SCSS, JavaScript, React Redux, Redux, Styled-components, Front-end

Senior React Native Developer

2019 - 2020

AAG Ventures

Produced MetaOne, a versatile React Native application compatible across platforms, designed to elevate productivity and cater to a diverse user audience.
Incorporated advanced task management and collaboration functionalities, resulting in favorable user responses and recommendations.
Enforced stringent security and data privacy measures, fostering a sense of trust and assurance among both users and stakeholders.
Effectively orchestrated development schedules and resources, guaranteeing punctual project completion and harmonious teamwork throughout the development process.

Technologies: React Native, Android, iOS, Jest, TypeScript, Figma, Jira, MetaMask, Slack, Agile, Redux, React, React Redux, React Query, Firebase, Sentry, Web3, Front-end

Senior Full-stack Developer

2018 - 2020

L'Officiel

Solely oversaw complete development lifecycles, encompassing React Native app, React back office, and Symfony API projects.
Instituted flawless data flow and real-time communication mechanisms, amplifying user engagement through heightened interactivity.
Enhanced app and API performance, leading to swift responsiveness and seamless user experiences.
Enforced robust security protocols to safeguard valuable data assets.
Furnished extensive documentation and prompt support, contributing to enriched user experiences.
Attained elevated app adoption rates and heightened user engagement, resulting in noteworthy expansion of the user base and improved business metrics.

Technologies: PHP, JavaScript, TypeScript, Firebase, Jira, AWS CLI, Symfony, React Native, iOS, Android, React, React Redux, Styled-components, Redux, React Query, Figma, HTML, CSS, Agile, Full-stack, Front-end, Back-end, Full-stack Development, SQL, MySQL, Startups, eCommerce

Full-stack Software Developer

2017 - 2018

Amerant Bank

Played a key role in the triumphant development of ASP.NET web applications at Amerant Bank.
Partook in agile methodologies and consistently drove enhancements within the development team.
Enhanced application performance to deliver superior user experiences.

Technologies: C#, .NET, ASP.NET, JavaScript, Agile, CSS, SCSS, HTML, HTML5, Front-end, Back-end

Experience

Budget App

https://github.com/Digital-Vilnius/budget-app

Budget app is for user or team budget managing and monitoring. It let users to create account, add members to account, assign roles to user, manage operations and see reports generate base on entry data.

The Poolit

A React Native-based mobile application for investments. All delivered code was tested using the Jest framework. I introduced the best TypeScript practices for React Navigation to the project. Dependencies were sorted using Lint. I also suggested changes to the code review process.

Circles

A React Native-based mobile application that provides online support for people. My main goal in the project was to create features for the mobile application. I worked on screen redesign, E2E testing, new features implementation, and bug fixing.

Crypto Wallet App

I independently developed a user-friendly cryptocurrency wallet app for Polkadot's testnet. Using React Native and TypeScript, I created features such as wallet management, fund transfers, and real-time balances. Following Figma designs, I ensured an intuitive user interface. The app's successful launch streamlined crypto interactions within the Polkadot ecosystem.

Mental Health Support App

A React Native-based mobile application that provides mental health support. It includes features such as an audio player, push notifications, chat, OpenAI integration, authentication, walkthrough, and many others. It was developed using a clean project structure and separated business logic from UI.

Education

2023 - 2023

Ph.D. in Software Engineering

Vilnius University - Vilnius, Lithuania

2019 - 2023

Master's Degree in Software Engineering

Vilnius University - Vilnius, Lithuania

2015 - 2019

Bachelor's Degree in Software Engineering

Vilnius University - Vilnius, Lithuania

Skills

Libraries/APIs

React, Node.js, React Navigation, React Redux, React Query, AutoMapper, MobX, Emotion Library, React Router, Google Maps

Tools

Expo, Jira, Figma, Slack, Expo.io, Redux Thunk, OneSignal, Sentry, MetaMask, AWS CLI, ChatGPT, CircleCI

Languages

C#, JavaScript, PHP, TypeScript, CSS, HTML5, HTML, SCSS, ECMAScript (ES6), SQL, Swift, Kotlin, C#.NET

Frameworks

Angular, React Native, Redux, .NET Core, Jest, ASP.NET, Tailwind CSS, Symfony, Laravel, Material UI, Next.js, .NET

Paradigms

Clean Code, Agile

Platforms

iOS, Android, Amazon Web Services (AWS), Firebase, Azure, Blockchain

Storage

Database Architecture, MySQL, Microsoft SQL Server, MongoDB

Other

Styled-components, Software, Engineering Software, Full-stack, Architecture, APIs, Front-end, Back-end, Full-stack Development, DOM, i18n, eCommerce, Data Visualization, Charts, Data Structures, CI/CD Pipelines, SDKs, FaceTec, Web3, Startups, WYSIWYG Web Builders, Domain-driven Design (DDD), OpenAI GPT-4 API, OpenAI GPT-3 API, Apple Pay, Google Pay

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