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Wojciech Jaszczak
Verified Expert in Engineering
Software Developer
Kutno, Poland
Toptal member since March 10, 2017
Bio
Wojciech is a solid software engineer with a master's degree in computer science and a strong understanding of the whole web stack. He has worked as both a full-stack and front-end developer and with technologies such as AngularJS, React, Redux, and Node.js. Wojciech has a friendly approach that allows him to fit well in teams. He was selected as a tech team leader on numerous occasions due to his technical and soft skills.
Portfolio
An Online Freelance Agency
JavaScript, React, Node.js, Go, Code Review, CSS, CSS3, HTML5, React Redux, Git...
Daily AI LLC
React, Node.js, TypeScript, Full-stack, Redux, GraphQL, Next.js, Tailwind CSS...
Prysm Financial Technology Inc
React, Redux, TypeScript, Front-end, React Hooks, UI Components...
Experience
- JavaScript - 11 years
- Git - 9 years
- CSS3 - 8 years
- Node.js - 6 years
- React - 6 years
- TypeScript - 6 years
- Redux - 5 years
- AngularJS - 3 years
Work Experience
Senior Full-stack Developer
2018 - PRESENT
An Online Freelance Agency
- Delivered multiple microservices written in Go, responsible for handling specific use cases in a live broadcasting platform.
- Designed and delivered a tool to manage live streaming for a global audience. The tool used a real-time updating system, CQRS, separation of responsibilities, and React for the front end. It was used to monitor and support big-scale events.
- Participated in an evaluation of multiple third-party service providers to assess what use cases they supported in our workflow and helped pick some of them, providing concise documentation of the findings and POCs.
Technologies: JavaScript, React, Node.js, Go, Code Review, CSS, CSS3, HTML5, React Redux, Git, TypeScript, GraphQL, Apollo, Sass, SCSS, Storybook, Netlify, PostgreSQL, Content Management Systems (CMS), Full-stack, Amazon Web Services (AWS), Software Design, MongoDB, React Components, React Hooks, APIs, API Integration, Chakra UI, Single-page Applications (SPAs), Back-end, Tailwind CSS, Microservices, Webpack, React Router, Cypress, REST APIs, Jest, Jenkins, Redux, Redux Toolkit, Unit Testing, Material UI, Back-end Development, CQRS, Automated Testing, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), AWS Lambda, OpenAI GPT-3 API, OpenAI GPT-4 API, ChatGPT, Puppeteer
Senior Full-stack React Developer
2022 - 2023
Daily AI LLC
- Implemented, based on Figma designs, workflow UI where users could define conditions and actions to be performed in response to actions.
- Implemented E2E tests in Cypress to cover the critical paths in the application.
- Implemented features on both the front end and the back end of the application. Added support for bulk actions for selected entities, from Figma designs to storing data in a PostgreSQL database.
Technologies: React, Node.js, TypeScript, Full-stack, Redux, GraphQL, Next.js, Tailwind CSS, Storybook, Serverless, Amazon Simple Notification Service (SNS), AWS Lambda
Front-end Developer
2022 - 2022
Prysm Financial Technology Inc
- Audited existing web applications created by a third company. Identified security risks for a fintech startup and created a plan to mitiage them.
- Removed SQL injections that were present in the application.
- Successfully launched to production MVP of an application, ensuring that security, scalability, and sanity concerns were sufficiently documented, known, or solved.
- Integrated 3rd party analytics solutions like Datadog and Amplitude.
Technologies: React, Redux, TypeScript, Front-end, React Hooks, UI Components, React Components, Netlify, Emotion Library, Fintech, Startups, Amazon Web Services (AWS), Kubernetes, API Integration, Single-page Applications (SPAs), Tailwind CSS, Server-side Rendering (SSR), Webpack, React Router, Testing, REST APIs, Redux Toolkit, Unit Testing, Material UI, NoSQL, User Interface (UI), CQRS, Amazon Simple Queue Service (SQS), AWS Lambda
Senior React Developer and Engineer
2021 - 2022
iptiQ Life S.A. UK Branch
- Created a white label React components library project.
- Analyzed and provided solutions regarding webhooks and event-driven communication with client applications.
- Worked on a solution for designing and improving an API for external customers of the services in production.
- Created mappers from RESTful services into GraphQL idiomatic schemas that allowed users to consume the API optimally.
Technologies: React, GraphQL, TypeScript, Apache Kafka, Architecture, React Components, React Hooks, Amazon Web Services (AWS), API Integration, Single-page Applications (SPAs), Server-side Rendering (SSR), React Router, Testing, REST APIs, Jest, Unit Testing, Material UI, Solution Architecture, Back-end Development, Automated Testing
React Developer
2020 - 2021
Recalibrated Bodies
- Configured and enhanced Strapi CMS for the customer's needs. Wrote custom GraphQL.
- Implemented support for subscription-based payment with handling on the CMS side.
- Integrated Stripe payments system with CMS to track payments and orders with products managed internally.
- Delivered full eCommerce web application, starting from Figma designs implemented as React application to the production release and payment system integration.
Technologies: React, Next.js, Stripe, Styled-components, Strapi
Freelance Front-end Engineer
2018 - 2018
Wilmaa
- Implemented a highly optimized HTML Canvas TV guide.
- Optimized the rendering performance of the virtualized lists with a focus on older systems and browsers.
- Re-implemented features from a Flash/AngularJS application into a modern React/Redux stack.
- Worked closely with the BA of the team to deliver a high-quality product for end-users, iterating on the solution to achieve the best results.
Technologies: JavaScript, Redux, React, HTML5, React Redux, Git, Sass, SCSS, Bootstrap, React Router, Testing, Unit Testing, NoSQL, User Interface (UI), CRDT
Front-end Engineer
2017 - 2018
TuneFind
- Implemented optimistic updates on most of the heavy user forms.
- Developed an "instant" load with the reuse of Redux data.
- Installed a header bidding to improve ad conversion rates.
- Created a reusable component for song submissions with storing user input on each step of their interactions.
- Developed and reviewed features based on user feedback.
Technologies: Architecture, JavaScript, Redux, React, Leadership, HTML5, Git, Sass, SCSS, Bootstrap, Amazon Web Services (AWS), Single-page Applications (SPAs), Server-side Rendering (SSR), React Router, REST APIs, Solution Architecture, User Interface (UI), Header Bidding
Freelance Full-stack Web Developer
2017 - 2017
ClassDojo
- Created a feature that allows users to draw on pictures taken with their webcam.
- Refactored the application's Node.js back end from callback-driven to Promises and after that to Koa.
- Developed a set of features based on WebRTC—recording video, recording audio, and taking pictures.
- Implemented new and simplified some of the older endpoints.
Technologies: JavaScript, Redux-Saga, Redux, React, Express.js, Node.js, TypeScript, HTML5, React Redux, Git, Full-stack, APIs, Back-end, Microservices, REST APIs, Jest, Back-end Development, CRDT, Automated Testing
Senior Full-stack Engineer
2016 - 2017
Roche
- Created a CRM system with AngularJS and RESTful services. Supported offline usage with WebSQL and iPad support via Cordova.
- Led a team that delivered a defined set of React components in the form of a library. It has a well-defined API, tests, and playground for each component to be able to test them fully.
- Created a scaffolding application showing the best practices of using Redux and React in creating a full web application. Designed the architecture that will be a standard for future products.
- Developed a real-time experience with React, Redux, Redux-saga, and stomp to communicate via Sockets with the Node.js server.
- Supported a team in maintaining AngularJS applications providing guidelines, best practices, and resolving specific issues.
Technologies: WebSockets, Software Architecture, Architecture, Web Architecture, SQL, Node.js, JavaScript, STOMP, Redux, React, AngularJS, Technical Support, Technical Leadership, TypeScript, Code Review, CSS, Team Leadership, HTML5, Git, SOLID Principles, PostgreSQL, Full-stack, Software Design, APIs, Back-end, Microservices, Jenkins, Solution Architecture, NoSQL, Back-end Development, CRDT, CQRS, Automated Testing
Full-stack Web Developer
2011 - 2015
EUVIC
- Created a custom date-picker that allows creating a range of periods.
- Optimized an SVG grid rendering engine written in C# by tenfold, analyzing the code complexity and optimizing SQL queries.
- Helped a team in need as a front-end supervisor, helping to deliver the product in a timely manner.
- Created and maintained interactions with the user—using custom elements of Knockout.js and JavaScript design patterns (e.g., strategy).
- Maintained a small .NET project—consulting future features with the client, providing estimates, and delivering them in given time frames.
Technologies: Software Architecture, Architecture, JavaScript, SQL, AngularJS, jQuery, C#, .NET, Knockout (Knockout.js), HTML, CSS, CSS3, HTML5, Git, SOLID Principles, Full-stack, Back-end, Microservices, NoSQL, Back-end Development, CQRS
Project History
Waytomaster
The idea of this project is to translate difficult English words in movies/series subtitles to any language (the native language of the user) to speed up the language learning process.
We advanced with NLP (Natural Language Processing) algorithms so that each of our users has their own set of known words that they could manage on their own. We then returned a new subtitle file, which was extended with translations for difficult words that the user could apply as any other subtitle.
I implemented natural language processing, AngularJS for the front end, and PostgreSQL for the database optimizations in the project. I also implemented a plugin into a third-party application that allowed the usage of the application directly in it.
We advanced with NLP (Natural Language Processing) algorithms so that each of our users has their own set of known words that they could manage on their own. We then returned a new subtitle file, which was extended with translations for difficult words that the user could apply as any other subtitle.
I implemented natural language processing, AngularJS for the front end, and PostgreSQL for the database optimizations in the project. I also implemented a plugin into a third-party application that allowed the usage of the application directly in it.
Tunefind
An application that allows users to find what song they had heard in the latest show or movie. I was the sole front-end developer for the website for about a year. The code was a mix of Redux-based components and archaic practices from React, as it was started almost six years ago. Therefore, I was initially responsible for migrating to a more sensible Redux solution and recently started migrating to Next.js for speed index improvements.
Snapshot Analytics
I was the technical leader for the front-end team. We implemented a solution that led to securing the next stages of funding.
The back end was designed to allow usage of different data providers—it was database agnostic and based on micro-services. The front end was a SPA in Knockout.js with custom elements and integrations with the D3.js library for clean and pretty chart visualizations.
The back end was designed to allow usage of different data providers—it was database agnostic and based on micro-services. The front end was a SPA in Knockout.js with custom elements and integrations with the D3.js library for clean and pretty chart visualizations.
Recalibrated Bodies
https://www.recalibratedbodies.com/A personal training and nutrition eCommerce platform.
The platform is used to sell nutrition and training programs to clients around the world.
A one-time sales and subscription model is implemented, integrated with Stripe payments and subscriptions.
After collaborating with the designer, I implemented the front end and set up CMS and Stripe integration.
The app is deployed as a set of docker-images in a VPS, which I have set up to limit the amount of costs and ease changing the hosting provider.
The stack:
Next.js, React, Strapi, Stripe, Sendgrid, PostgreSQL, Recoil.js
The platform is used to sell nutrition and training programs to clients around the world.
A one-time sales and subscription model is implemented, integrated with Stripe payments and subscriptions.
After collaborating with the designer, I implemented the front end and set up CMS and Stripe integration.
The app is deployed as a set of docker-images in a VPS, which I have set up to limit the amount of costs and ease changing the hosting provider.
The stack:
Next.js, React, Strapi, Stripe, Sendgrid, PostgreSQL, Recoil.js
Education
2011 - 2015
Master of Science Degree in Computer Science
Silesian University of Technology - Gliwice, Poland
Skills
Libraries/APIs
Node.js, React, Redux-Saga, React Redux, REST APIs, React Router, Puppeteer, jQuery, WebRTC, Stripe, Stanford NLP, Emotion Library
Tools
Git, Webpack, Jenkins, Redux Toolkit, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), ChatGPT, WebStorm, Gulp, SendGrid
Languages
Go, JavaScript, HTML, CSS3, HTML5, TypeScript, CSS, C#, SQL, GraphQL, Sass, SCSS
Frameworks
Redux, AngularJS, Next.js, Express.js, Bootstrap, Tailwind CSS, Jest, Material UI, Knockout (Knockout.js), .NET, Cypress
Paradigms
Microservices, Unit Testing, Web Architecture, CQRS, Automated Testing, Testing, STOMP, Test-driven Development (TDD), Functional Programming
Platforms
Amazon Web Services (AWS), AWS Lambda, Windows, Netlify, Apache Kafka, Azure, Kubernetes, Visual Studio Code (VS Code)
Storage
PostgreSQL, NoSQL, MongoDB
Other
Web Applications, Architecture, Front-end, Code Review, React Components, React Hooks, APIs, API Integration, Single-page Applications (SPAs), Server-side Rendering (SSR), Back-end Development, Software Architecture, Web Development, WebSockets, SOLID Principles, Technical Support, Technical Leadership, Apollo, Storybook, Content Management Systems (CMS), Full-stack, Strapi, Software Design, Back-end, Solution Architecture, User Interface (UI), CRDT, OpenAI GPT-3 API, OpenAI GPT-4 API, Redux-observable, Domain-driven Design (DDD), Leadership, Team Leadership, UI Components, Fintech, Startups, Chakra UI, Styled-components, Serverless, Header Bidding
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